Method and device for requesting partial information from aps within transmission mld in wireless lan system

ABSTRACT

Proposed are a method and a device for requesting partial information from APs within a transmission MLD in a WLAN system. Particularly, a reception MLD transmits a probe request frame to a transmission MLD via a first link. The reception MLD receives a probe response frame from the transmission MLD via the first link. When the partial information regarding the first link and the partial information regarding the second link are the same, the partial information regarding the second link is requested on the basis of the first request element, and a value of a first full information profile sub-field is set to 0.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/KR2021/013415, filed on Sep. 30, 2021, which claims the benefit ofearlier filing date and right of priority to Korean Patent ApplicationNos. 10-2020-0168899, filed on Dec. 4, 2020, and 10-2020-0171536, filedon Dec. 9, 2020, the contents of which are hereby incorporated byreference herein in their entireties.

TECHNICAL FIELD

The present specification relates to a multi-link operation in awireless LAN system, and more particularly, to a method and apparatusfor requesting partial information from APs in a transmitting MLD.

BACKGROUND

A wireless local area network (WLAN) has been improved in various ways.For example, the IEEE 802.11ax standard proposed an improvedcommunication environment using orthogonal frequency division multipleaccess (OFDMA) and downlink multi-user multiple input multiple output(DL MU MIMO) techniques.

The present specification proposes a technical feature that can beutilized in a new communication standard. For example, the newcommunication standard may be an extreme high throughput (EHT) standardwhich is currently being discussed. The EHT standard may use anincreased bandwidth, an enhanced PHY layer protocol data unit (PPDU)structure, an enhanced sequence, a hybrid automatic repeat request(HARQ) scheme, or the like, which is newly proposed. The EHT standardmay be called the IEEE 802.11be standard.

In a new WLAN standard, an increased number of spatial streams may beused. In this case, in order to properly use the increased number ofspatial streams, a signaling technique in the WLAN system may need to beimproved.

SUMMARY

The present specification proposes a method and apparatus for requestingpartial information from APs in a transmitting MLD in a wireless LANsystem.

An example of this specification proposes a method for requestingpartial information from APs in a transmitting MLD.

The present embodiment may be performed in a network environment inwhich a next generation WLAN system (IEEE 802.11be or EHT WLAN system)is supported. The next generation wireless LAN system is a WLAN systemthat is enhanced from an 802.11ax system and may, therefore, satisfybackward compatibility with the 802.11ax system.

In this embodiment, when a non-AP STA requests the same partialinformation as a peer AP for an AP other than a peer AP in MLDcommunication, a method and apparatus for transmitting a probe requestframe or receiving a probe response frame by omitting an (Extended)Request element in a profile field of another AP are proposed. Here, thetransmitting MLD may correspond to the AP MLD, and the receiving MLD maycorrespond to the non-AP MLD. If the non-AP STA is a first receivingSTA, a first transmitting STA connected to the first receiving STAthrough a first link may be referred to as a peer AP, and the second tofourth transmitting STAs connected through different links may bereferred to as different APs.

A receiving multi-link device (MLD) transmits a probe request frame to atransmitting MLD through a first link.

The receiving MLD receives a probe response frame from the transmittingMLD through the first link.

The transmitting MLD includes a first transmitting station (STA)operating on the first link and a second transmitting STA operating on asecond link. The receiving MLD includes a first receiving STA operatingon the first link and a second receiving STA operating on the secondlink.

When the first receiving STA requests partial information on the firstand second links, the probe request frame includes a first requestelement and a multi-link element.

Partial information on the first link is requested based on the firstrequest element. The first request element is an (Extended) RequestElement and may be included in a frame body of the probe request frameinstead of being included in the multi-link element. That is, when thefirst receiving STA requests partial information on the firsttransmitting STA (peer AP), the first request element may be included inthe probe request frame, and information may be specified for eachelement identifier (element ID) in the first request element. However,when the first receiving STA requests complete information on the firsttransmitting STA, the first request element may not be included in theprobe request frame. The first transmitting STA may confirm that thefirst receiving STA is requesting the complete information because thefirst request element is not included in the probe request frame.

The multi-link element includes a profile field of the second receivingSTA. That is, the multi-link element can be used when requestinginformation on an AP other than a peer AP.

The profile field of the second receiving STA includes a first completeinformation profile subfield.

When partial information on the first link and partial information onthe second link are the same, partial information on the second link isrequested based on the first request element, and a value of the firstcomplete information profile subfield is set to 0. That is, when thefirst receiving STA requests the same partial information as the firstlink for the second link, since partial information on the second linkcan be requested through the first request element ((Extended) RequestElement) included in the probe request frame, since the partialinformation on the second link can be requested through the firstrequest element ((Extended) Request Element) included in the proberequest frame, a profile field of the second receiving STA may betransmitted without including a separate (Extended) Request Element.However, the value of the first complete information profile subfieldmay be set to 0 to notify the second transmitting STA that partialinformation is being requested for the second link. This method may bereferred to as a method in which an inheritance model is applied to a(MLD) probe request frame.

According to the embodiment proposed in this specification, whenrequesting the same partial information as the peer AP for the other AP,it is possible to omit the (Extended) Request Element in the profilefield of the other AP, thereby preventing unnecessary duplication ofinformation. This has the effect of reducing the overall frame overhead.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a transmitting apparatus and/or receivingapparatus of the present specification.

FIG. 2 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

FIG. 3 illustrates a general link setup process.

FIG. 4 illustrates an example of a PPDU used in an IEEE standard.

FIG. 5 illustrates an operation based on UL-MU.

FIG. 6 illustrates an example of a trigger frame.

FIG. 7 illustrates an example of a common information field of a triggerframe.

FIG. 8 illustrates an example of a subfield included in a per userinformation field.

FIG. 9 describes a technical feature of the UORA scheme.

FIG. 10 illustrates an example of a PPDU used in the presentspecification.

FIG. 11 illustrates an example of a modified transmission device and/orreceiving device of the present specification.

FIG. 12 shows an example of a structure of a non-AP MLD.

FIG. 13 illustrates an example in which an AP MLD and a non-AP MLD areconnected through a link setup process.

FIG. 14 illustrates an example in which Link is changed or reconnected.

FIG. 15 illustrates a specific example in which Link is changed orreconnected.

FIG. 16 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

FIG. 17 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

FIG. 18 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

FIG. 19 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

FIG. 20 illustrates an operation of a non-AP MLD for requestinginformation on other APs.

FIG. 21 shows a specific example of STA ratio per Link.

FIG. 22 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

FIG. 23 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

FIG. 24 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

FIG. 25 shows an example of a multi-link element added in a proberequest.

FIG. 26 shows an example of using a Link Range field in a multi-linkelement.

FIG. 27 shows an example of a newly proposed field to indicate linkchange and reconnection.

FIG. 28 shows an example of the Request IE format.

FIG. 29 shows an example of the Extended Request IE format.

FIG. 30 shows an example of a PV1 Probe Response Option element format.

FIG. 31 shows an example of an MLD Request element.

FIG. 32 shows another example of an MLD Request element.

FIG. 33 shows an example of defining a new element based on an MLDRequest element.

FIG. 34 shows another example of an MLD Request element.

FIG. 35 shows another example of an MLD Request element.

FIG. 36 shows another example of an MLD Request element.

FIG. 37 shows another example of an MLD Request element.

FIG. 38 shows an example of a field requesting common information.

FIG. 39 shows an example of the ML IE format defined in 802.11be.

FIG. 40 shows an example of a multi-link element format and a multi-linkcontrol field format.

FIG. 41 shows an example of a multi-link control field format.

FIG. 42 shows an example of the ML IE format.

FIG. 43 shows another example of the ML IE format.

FIG. 44 shows another example of the ML IE format.

FIG. 45 shows another example of the ML IE format.

FIG. 46 shows an example of a Probe Request frame including an ML IEformat.

FIG. 47 shows another example of a Probe Request frame including an MLIE format.

FIG. 48 shows another example of a Probe Request frame including an MLIE format.

FIG. 49 shows another example of a Probe Request frame including an MLIE format.

FIG. 50 shows an example of a Multi-link Control field format.

FIG. 51 shows an example in which the Critical update request field isincluded in the ML IE format.

FIG. 52 shows an example of an MLD probe request using a change sequenceelement when requesting critical update information.

FIG. 53 shows another example of an MLD probe request using a changesequence element when requesting critical update information.

FIG. 54 shows an example in which the Critical update request field isincluded in the ML IE format.

FIG. 55 shows an example in which a Change sequence element is includedin the ML IE format.

FIG. 56 shows an example of an MLD Change Sequence format.

FIG. 57 shows another example of an MLD Change Sequence format.

FIG. 58 shows an example of an MLD Change Sequence element.

FIG. 59 shows an example of a change sequence element in the existingstandard.

FIG. 60 shows another example in which a change sequence element isincluded in the ML IE format.

FIG. 61 shows an example of a probe request frame for requestingcritical update information.

FIG. 62 shows another example of a probe request frame for requestingcritical update information.

FIG. 63 shows another example of a probe request frame for requestingcritical update information.

FIG. 64 shows another example of a probe request frame for requestingcritical update information.

FIG. 65 is a flowchart illustrating a procedure in which a transmittingMLD provides requested information of an AP to a receiving MLD based ona probe response frame according to the present embodiment.

FIG. 66 is a flowchart illustrating a procedure for a receiving MLD torequest information of an AP from a transmitting MLD based on a proberequest frame according to the present embodiment.

DETAILED DESCRIPTION

In the present specification, “A or B” may mean “only A”, “only B” or“both A and B”. In other words, in the present specification, “A or B”may be interpreted as “A and/or B”. For example, in the presentspecification, “A, B, or C” may mean “only A”, “only B”, “only C”, or“any combination of A, B, C”.

A slash (/) or comma used in the present specification may mean“and/or”. For example, “A/B” may mean “A and/or B”. Accordingly, “A/B”may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C”may mean “A, B, or C”.

In the present specification, “at least one of A and B” may mean “onlyA”, “only B”, or “both A and B”. In addition, in the presentspecification, the expression “at least one of A or B” or “at least oneof A and/or B” may be interpreted as “at least one of A and B”.

In addition, in the present specification, “at least one of A, B, and C”may mean “only A”, “only B”, “only C”, or “any combination of A, B, andC”. In addition, “at least one of A, B, or C” or “at least one of A, B,and/or C” may mean “at least one of A, B, and C”.

In addition, a parenthesis used in the present specification may mean“for example”. Specifically, when indicated as “control information(EHT-signal)”, it may denote that “EHT-signal” is proposed as an exampleof the “control information”. In other words, the “control information”of the present specification is not limited to “EHT-signal”, and“EHT-signal” may be proposed as an example of the “control information”.In addition, when indicated as “control information (i.e., EHT-signal)”,it may also mean that “EHT-signal” is proposed as an example of the“control information”.

Technical features described individually in one figure in the presentspecification may be individually implemented, or may be simultaneouslyimplemented.

The following example of the present specification may be applied tovarious wireless communication systems. For example, the followingexample of the present specification may be applied to a wireless localarea network (WLAN) system. For example, the present specification maybe applied to the IEEE 802.11a/g/n/ac standard or the IEEE 802.11axstandard. In addition, the present specification may also be applied tothe newly proposed EHT standard or IEEE 802.11be standard. In addition,the example of the present specification may also be applied to a newWLAN standard enhanced from the EHT standard or the IEEE 802.11bestandard. In addition, the example of the present specification may beapplied to a mobile communication system. For example, it may be appliedto a mobile communication system based on long term evolution (LTE)depending on a 3rd generation partnership project (3GPP) standard andbased on evolution of the LTE. In addition, the example of the presentspecification may be applied to a communication system of a 5G NRstandard based on the 3GPP standard.

Hereinafter, in order to describe a technical feature of the presentspecification, a technical feature applicable to the presentspecification will be described.

FIG. 1 shows an example of a transmitting apparatus and/or receivingapparatus of the present specification.

In the example of FIG. 1 , various technical features described belowmay be performed. FIG. 1 relates to at least one station (STA). Forexample, STAs 110 and 120 of the present specification may also becalled in various terms such as a mobile terminal, a wireless device, awireless transmit/receive unit (WTRU), a user equipment (UE), a mobilestation (MS), a mobile subscriber unit, or simply a user. The STAs 110and 120 of the present specification may also be called in various termssuch as a network, a base station, a node-B, an access point (AP), arepeater, a router, a relay, or the like. The STAs 110 and 120 of thepresent specification may also be referred to as various names such as areceiving apparatus, a transmitting apparatus, a receiving STA, atransmitting STA, a receiving device, a transmitting device, or thelike.

For example, the STAs 110 and 120 may serve as an AP or a non-AP. Thatis, the STAs 110 and 120 of the present specification may serve as theAP and/or the non-AP.

The STAs 110 and 120 of the present specification may support variouscommunication standards together in addition to the IEEE 802.11standard. For example, a communication standard (e.g., LTE, LTE-A, 5G NRstandard) or the like based on the 3GPP standard may be supported. Inaddition, the STA of the present specification may be implemented asvarious devices such as a mobile phone, a vehicle, a personal computer,or the like. In addition, the STA of the present specification maysupport communication for various communication services such as voicecalls, video calls, data communication, and self-driving(autonomous-driving), or the like.

The STAs 110 and 120 of the present specification may include a mediumaccess control (MAC) conforming to the IEEE 802.11 standard and aphysical layer interface for a radio medium.

The STAs 110 and 120 will be described below with reference to asub-figure (a) of FIG. 1 .

The first STA 110 may include a processor 111, a memory 112, and atransceiver 113. The illustrated process, memory, and transceiver may beimplemented individually as separate chips, or at least twoblocks/functions may be implemented through a single chip.

The transceiver 113 of the first STA performs a signaltransmission/reception operation. Specifically, an IEEE 802.11 packet(e.g., IEEE 802.11a/b/g/n/ac/ax/be, etc.) may be transmitted/received.

For example, the first STA 110 may perform an operation intended by anAP. For example, the processor 111 of the AP may receive a signalthrough the transceiver 113, process a reception (RX) signal, generate atransmission (TX) signal, and provide control for signal transmission.The memory 112 of the AP may store a signal (e.g., RX signal) receivedthrough the transceiver 113, and may store a signal (e.g., TX signal) tobe transmitted through the transceiver.

For example, the second STA 120 may perform an operation intended by anon-AP STA. For example, a transceiver 123 of a non-AP performs a signaltransmission/reception operation. Specifically, an IEEE 802.11 packet(e.g., IEEE 802.11a/b/g/n/ac/ax/be packet, etc.) may betransmitted/received.

For example, a processor 121 of the non-AP STA may receive a signalthrough the transceiver 123, process an RX signal, generate a TX signal,and provide control for signal transmission. A memory 122 of the non-APSTA may store a signal (e.g., RX signal) received through thetransceiver 123, and may store a signal (e.g., TX signal) to betransmitted through the transceiver.

For example, an operation of a device indicated as an AP in thespecification described below may be performed in the first STA 110 orthe second STA 120. For example, if the first STA 110 is the AP, theoperation of the device indicated as the AP may be controlled by theprocessor 111 of the first STA 110, and a related signal may betransmitted or received through the transceiver 113 controlled by theprocessor 111 of the first STA 110. In addition, control informationrelated to the operation of the AP or a TX/RX signal of the AP may bestored in the memory 112 of the first STA 110. In addition, if thesecond STA 120 is the AP, the operation of the device indicated as theAP may be controlled by the processor 121 of the second STA 120, and arelated signal may be transmitted or received through the transceiver123 controlled by the processor 121 of the second STA 120. In addition,control information related to the operation of the AP or a TX/RX signalof the AP may be stored in the memory 122 of the second STA 120.

For example, in the specification described below, an operation of adevice indicated as a non-AP (or user-STA) may be performed in the firstSTA 110 or the second STA 120. For example, if the second STA 120 is thenon-AP, the operation of the device indicated as the non-AP may becontrolled by the processor 121 of the second STA 120, and a relatedsignal may be transmitted or received through the transceiver 123controlled by the processor 121 of the second STA 120. In addition,control information related to the operation of the non-AP or a TX/RXsignal of the non-AP may be stored in the memory 122 of the second STA120. For example, if the first STA 110 is the non-AP, the operation ofthe device indicated as the non-AP may be controlled by the processor111 of the first STA 110, and a related signal may be transmitted orreceived through the transceiver 113 controlled by the processor 111 ofthe first STA 110. In addition, control information related to theoperation of the non-AP or a TX/RX signal of the non-AP may be stored inthe memory 112 of the first STA 110.

In the specification described below, a device called a(transmitting/receiving) STA, a first STA, a second STA, a STA1, a STA2,an AP, a first AP, a second AP, an AP1, an AP2, a(transmitting/receiving) terminal, a (transmitting/receiving) device, a(transmitting/receiving) apparatus, a network, or the like may imply theSTAs 110 and 120 of FIG. 1 . For example, a device indicated as, withouta specific reference numeral, the (transmitting/receiving) STA, thefirst STA, the second STA, the STA1, the STA2, the AP, the first AP, thesecond AP, the AP1, the AP2, the (transmitting/receiving) terminal, the(transmitting/receiving) device, the (transmitting/receiving) apparatus,the network, or the like may imply the STAs 110 and 120 of FIG. 1 . Forexample, in the following example, an operation in which various STAstransmit/receive a signal (e.g., a PPDU) may be performed in thetransceivers 113 and 123 of FIG. 1 . In addition, in the followingexample, an operation in which various STAs generate a TX/RX signal orperform data processing and computation in advance for the TX/RX signalmay be performed in the processors 111 and 121 of FIG. 1 . For example,an example of an operation for generating the TX/RX signal or performingthe data processing and computation in advance may include: 1) anoperation ofdetermining/obtaining/configuring/computing/decoding/encoding bitinformation of a sub-field (SIG, STF, LTF, Data) included in a PPDU; 2)an operation of determining/configuring/obtaining a time resource orfrequency resource (e.g., a subcarrier resource) or the like used forthe sub-field (SIG, STF, LTF, Data) included the PPDU; 3) an operationof determining/configuring/obtaining a specific sequence (e.g., a pilotsequence, an STF/LTF sequence, an extra sequence applied to SIG) or thelike used for the sub-field (SIG, STF, LTF, Data) field included in thePPDU; 4) a power control operation and/or power saving operation appliedfor the STA; and 5) an operation related todetermining/obtaining/configuring/decoding/encoding or the like of anACK signal. In addition, in the following example, a variety ofinformation used by various STAs fordetermining/obtaining/configuring/computing/decoding/decoding a TX/RXsignal (e.g., information related to a field/subfield/controlfield/parameter/power or the like) may be stored in the memories 112 and122 of FIG. 1 .

The aforementioned device/STA of the sub-figure (a) of FIG. 1 may bemodified as shown in the sub-figure (b) of FIG. 1 . Hereinafter, theSTAs 110 and 120 of the present specification will be described based onthe sub-figure (b) of FIG. 1 .

For example, the transceivers 113 and 123 illustrated in the sub-figure(b) of FIG. 1 may perform the same function as the aforementionedtransceiver illustrated in the sub-figure (a) of FIG. 1 . For example,processing chips 114 and 124 illustrated in the sub-figure (b) of FIG. 1may include the processors 111 and 121 and the memories 112 and 122. Theprocessors 111 and 121 and memories 112 and 122 illustrated in thesub-figure (b) of FIG. 1 may perform the same function as theaforementioned processors 111 and 121 and memories 112 and 122illustrated in the sub-figure (a) of FIG. 1 .

A mobile terminal, a wireless device, a wireless transmit/receive unit(WTRU), a user equipment (UE), a mobile station (MS), a mobilesubscriber unit, a user, a user STA, a network, a base station, aNode-B, an access point (AP), a repeater, a router, a relay, a receivingunit, a transmitting unit, a receiving STA, a transmitting STA, areceiving device, a transmitting device, a receiving apparatus, and/or atransmitting apparatus, which are described below, may imply the STAs110 and 120 illustrated in the sub-figure (a)/(b) of FIG. 1 , or mayimply the processing chips 114 and 124 illustrated in the sub-figure (b)of FIG. 1 . That is, a technical feature of the present specificationmay be performed in the STAs 110 and 120 illustrated in the sub-figure(a)/(b) of FIG. 1 , or may be performed only in the processing chips 114and 124 illustrated in the sub-figure (b) of FIG. 1 . For example, atechnical feature in which the transmitting STA transmits a controlsignal may be understood as a technical feature in which a controlsignal generated in the processors 111 and 121 illustrated in thesub-figure (a)/(b) of FIG. 1 is transmitted through the transceivers 113and 123 illustrated in the sub-figure (a)/(b) of FIG. 1 . Alternatively,the technical feature in which the transmitting STA transmits thecontrol signal may be understood as a technical feature in which thecontrol signal to be transferred to the transceivers 113 and 123 isgenerated in the processing chips 114 and 124 illustrated in thesub-figure (b) of FIG. 1 .

For example, a technical feature in which the receiving STA receives thecontrol signal may be understood as a technical feature in which thecontrol signal is received by means of the transceivers 113 and 123illustrated in the sub-figure (a) of FIG. 1 . Alternatively, thetechnical feature in which the receiving STA receives the control signalmay be understood as the technical feature in which the control signalreceived in the transceivers 113 and 123 illustrated in the sub-figure(a) of FIG. 1 is obtained by the processors 111 and 121 illustrated inthe sub-figure (a) of FIG. 1 . Alternatively, the technical feature inwhich the receiving STA receives the control signal may be understood asthe technical feature in which the control signal received in thetransceivers 113 and 123 illustrated in the sub-figure (b) of FIG. 1 isobtained by the processing chips 114 and 124 illustrated in thesub-figure (b) of FIG. 1 .

Referring to the sub-figure (b) of FIG. 1 , software codes 115 and 125may be included in the memories 112 and 122. The software codes 115 and126 may include instructions for controlling an operation of theprocessors 111 and 121. The software codes 115 and 125 may be includedas various programming languages.

The processors 111 and 121 or processing chips 114 and 124 of FIG. 1 mayinclude an application-specific integrated circuit (ASIC), otherchipsets, a logic circuit and/or a data processing device. The processormay be an application processor (AP). For example, the processors 111and 121 or processing chips 114 and 124 of FIG. 1 may include at leastone of a digital signal processor (DSP), a central processing unit(CPU), a graphics processing unit (GPU), and a modulator and demodulator(modem). For example, the processors 111 and 121 or processing chips 114and 124 of FIG. 1 may be SNAPDRAGON™ series of processors made byQualcomm®, EXYNOS™ series of processors made by Samsung®, A series ofprocessors made by Apple®, HELIO™ series of processors made byMediaTek®, ATOM™ series of processors made by Intel® or processorsenhanced from these processors.

In the present specification, an uplink may imply a link forcommunication from a non-AP STA to an SP STA, and an uplinkPPDU/packet/signal or the like may be transmitted through the uplink. Inaddition, in the present specification, a downlink may imply a link forcommunication from the AP STA to the non-AP STA, and a downlinkPPDU/packet/signal or the like may be transmitted through the downlink.

FIG. 2 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

An upper part of FIG. 2 illustrates the structure of an infrastructurebasic service set (BSS) of institute of electrical and electronicengineers (IEEE) 802.11.

Referring the upper part of FIG. 2 , the wireless LAN system may includeone or more infrastructure BSSs 200 and 205 (hereinafter, referred to asBSS). The BSSs 200 and 205 as a set of an AP and a STA such as an accesspoint (AP) 225 and a station (STA1) 200-1 which are successfullysynchronized to communicate with each other are not concepts indicatinga specific region. The BSS 205 may include one or more STAs 205-1 and205-2 which may be joined to one AP 230.

The BSS may include at least one STA, APs providing a distributionservice, and a distribution system (DS) 210 connecting multiple APs.

The distribution system 210 may implement an extended service set (ESS)240 extended by connecting the multiple BSSs 200 and 205. The ESS 240may be used as a term indicating one network configured by connectingone or more APs 225 or 230 through the distribution system 210. The APincluded in one ESS 240 may have the same service set identification(SSID).

A portal 220 may serve as a bridge which connects the wireless LANnetwork (IEEE 802.11) and another network (e.g., 802.X).

In the BSS illustrated in the upper part of FIG. 2 , a network betweenthe APs 225 and 230 and a network between the APs 225 and 230 and theSTAs 200-1, 205-1, and 205-2 may be implemented. However, the network isconfigured even between the STAs without the APs 225 and 230 to performcommunication. A network in which the communication is performed byconfiguring the network even between the STAs without the APs 225 and230 is defined as an Ad-Hoc network or an independent basic service set(IBSS).

A lower part of FIG. 2 illustrates a conceptual view illustrating theIBSS.

Referring to the lower part of FIG. 2 , the IBSS is a BSS that operatesin an Ad-Hoc mode. Since the IBSS does not include the access point(AP), a centralized management entity that performs a managementfunction at the center does not exist. That is, in the IBSS, STAs 250-1,250-2, 250-3, 255-4, and 255-5 are managed by a distributed manner. Inthe IBSS, all STAs 250-1, 250-2, 250-3, 255-4, and 255-5 may beconstituted by movable STAs and are not permitted to access the DS toconstitute a self-contained network.

FIG. 3 illustrates a general link setup process.

In S310, a STA may perform a network discovery operation. The networkdiscovery operation may include a scanning operation of the STA. Thatis, to access a network, the STA needs to discover a participatingnetwork. The STA needs to identify a compatible network beforeparticipating in a wireless network, and a process of identifying anetwork present in a particular area is referred to as scanning.Scanning methods include active scanning and passive scanning.

FIG. 3 illustrates a network discovery operation including an activescanning process. In active scanning, a STA performing scanningtransmits a probe request frame and waits for a response to the proberequest frame in order to identify which AP is present around whilemoving to channels. A responder transmits a probe response frame as aresponse to the probe request frame to the STA having transmitted theprobe request frame. Here, the responder may be a STA that transmits thelast beacon frame in a BSS of a channel being scanned. In the BSS, sincean AP transmits a beacon frame, the AP is the responder. In an IBSS,since STAs in the IBSS transmit a beacon frame in turns, the responderis not fixed. For example, when the STA transmits a probe request framevia channel 1 and receives a probe response frame via channel 1, the STAmay store BSS-related information included in the received proberesponse frame, may move to the next channel (e.g., channel 2), and mayperform scanning (e.g., transmits a probe request and receives a proberesponse via channel 2) by the same method.

Although not shown in FIG. 3 , scanning may be performed by a passivescanning method. In passive scanning, a STA performing scanning may waitfor a beacon frame while moving to channels. A beacon frame is one ofmanagement frames in IEEE 802.11 and is periodically transmitted toindicate the presence of a wireless network and to enable the STAperforming scanning to find the wireless network and to participate inthe wireless network. In a BSS, an AP serves to periodically transmit abeacon frame. In an IBSS, STAs in the IBSS transmit a beacon frame inturns. Upon receiving the beacon frame, the STA performing scanningstores information related to a BSS included in the beacon frame andrecords beacon frame information in each channel while moving to anotherchannel. The STA having received the beacon frame may store BSS-relatedinformation included in the received beacon frame, may move to the nextchannel, and may perform scanning in the next channel by the samemethod.

After discovering the network, the STA may perform an authenticationprocess in S320. The authentication process may be referred to as afirst authentication process to be clearly distinguished from thefollowing security setup operation in S340. The authentication processin S320 may include a process in which the STA transmits anauthentication request frame to the AP and the AP transmits anauthentication response frame to the STA in response. The authenticationframes used for an authentication request/response are managementframes.

The authentication frames may include information related to anauthentication algorithm number, an authentication transaction sequencenumber, a status code, a challenge text, a robust security network(RSN), and a finite cyclic group.

The STA may transmit the authentication request frame to the AP. The APmay determine whether to allow the authentication of the STA based onthe information included in the received authentication request frame.The AP may provide the authentication processing result to the STA viathe authentication response frame.

When the STA is successfully authenticated, the STA may perform anassociation process in S330. The association process includes a processin which the STA transmits an association request frame to the AP andthe AP transmits an association response frame to the STA in response.The association request frame may include, for example, informationrelated to various capabilities, a beacon listen interval, a service setidentifier (SSID), a supported rate, a supported channel, RSN, amobility domain, a supported operating class, a traffic indication map(TIM) broadcast request, and an interworking service capability. Theassociation response frame may include, for example, information relatedto various capabilities, a status code, an association ID (AID), asupported rate, an enhanced distributed channel access (EDCA) parameterset, a received channel power indicator (RCPI), a receivedsignal-to-noise indicator (RSNI), a mobility domain, a timeout interval(association comeback time), an overlapping BSS scanning parameter, aTIM broadcast response, and a QoS map.

In S340, the STA may perform a security setup process. The securitysetup process in S340 may include a process of setting up a private keythrough four-way handshaking, for example, through an extensibleauthentication protocol over LAN (EAPOL) frame.

FIG. 4 illustrates an example of a PPDU used in an IEEE standard.

As illustrated, various types of PHY protocol data units (PPDUs) areused in IEEE a/g/n/ac standards. Specifically, an LTF and a STF includea training signal, a SIG-A and a SIG-B include control information for areceiving STA, and a data field includes user data corresponding to aPSDU (MAC PDU/aggregated MAC PDU).

FIG. 4 also includes an example of an HE PPDU according to IEEE802.11ax. The HE PPDU according to FIG. 4 is an illustrative PPDU formultiple users. An HE-SIG-B may be included only in a PPDU for multipleusers, and an HE-SIG-B may be omitted in a PPDU for a single user.

As illustrated in FIG. 4 , the HE-PPDU for multiple users (MUs) mayinclude a legacy-short training field (L-STF), a legacy-long trainingfield (L-LTF), a legacy-signal (L-SIG), a high efficiency-signal A(HE-SIG A), a high efficiency-signal-B (HE-SIG B), a highefficiency-short training field (HE-STF), a high efficiency-longtraining field (HE-LTF), a data field (alternatively, an MAC payload),and a packet extension (PE) field. The respective fields may betransmitted for illustrated time periods (i.e., 4 or 8 μs).

Hereinafter, a resource unit (RU) used for a PPDU is described. An RUmay include a plurality of subcarriers (or tones). An RU may be used totransmit a signal to a plurality of STAs according to OFDMA. Further, anRU may also be defined to transmit a signal to one STA. An RU may beused for an STF, an LTF, a data field, or the like.

The RU described in the present specification may be used in uplink (UL)communication and downlink (DL) communication. For example, when UL-MUcommunication which is solicited by a trigger frame is performed, atransmitting STA (e.g., an AP) may allocate a first RU (e.g.,26/52/106/242-RU, etc.) to a first STA through the trigger frame, andmay allocate a second RU (e.g., 26/52/106/242-RU, etc.) to a second STA.Thereafter, the first STA may transmit a first trigger-based PPDU basedon the first RU, and the second STA may transmit a second trigger-basedPPDU based on the second RU. The first/second trigger-based PPDU istransmitted to the AP at the same (or overlapped) time period.

For example, when a DL MU PPDU is configured, the transmitting STA(e.g., AP) may allocate the first RU (e.g., 26/52/106/242-RU. etc.) tothe first STA, and may allocate the second RU (e.g., 26/52/106/242-RU,etc.) to the second STA. That is, the transmitting STA (e.g., AP) maytransmit HE-STF, HE-LTF, and Data fields for the first STA through thefirst RU in one MU PPDU, and may transmit HE-STF, HE-LTF, and Datafields for the second STA through the second RU.

FIG. 5 illustrates an operation based on UL-MU. As illustrated, atransmitting STA (e.g., an AP) may perform channel access throughcontending (e.g., a backoff operation), and may transmit a trigger frame1030. That is, the transmitting STA may transmit a PPDU including thetrigger frame 1030. Upon receiving the PPDU including the trigger frame,a trigger-based (TB) PPDU is transmitted after a delay corresponding toSIFS.

TB PPDUs 1041 and 1042 may be transmitted at the same time period, andmay be transmitted from a plurality of STAs (e.g., user STAs) havingAIDs indicated in the trigger frame 1030. An ACK frame 1050 for the TBPPDU may be implemented in various forms.

A specific feature of the trigger frame is described with reference toFIG. 6 to FIG. 8 . Even if UL-MU communication is used, an orthogonalfrequency division multiple access (OFDMA) scheme or a MU MIMO schememay be used, and the OFDMA and MU-MIMO schemes may be simultaneouslyused.

FIG. 6 illustrates an example of a trigger frame. The trigger frame ofFIG. 6 allocates a resource for uplink multiple-user (MU) transmission,and may be transmitted, for example, from an AP. The trigger frame maybe configured of a MAC frame, and may be included in a PPDU.

Each field shown in FIG. 6 may be partially omitted, and another fieldmay be added. In addition, a length of each field may be changed to bedifferent from that shown in the figure.

A frame control field 1110 of FIG. 6 may include information related toa MAC protocol version and extra additional control information. Aduration field 1120 may include time information for NAV configurationor information related to an identifier (e.g., AID) of a STA.

In addition, an RA field 1130 may include address information of areceiving STA of a corresponding trigger frame, and may be optionallyomitted. A TA field 1140 may include address information of a STA (e.g.,an AP) which transmits the corresponding trigger frame. A commoninformation field 1150 includes common control information applied tothe receiving STA which receives the corresponding trigger frame. Forexample, a field indicating a length of an L-SIG field of an uplink PPDUtransmitted in response to the corresponding trigger frame orinformation for controlling content of a SIG-A field (i.e., HE-SIG-Afield) of the uplink PPDU transmitted in response to the correspondingtrigger frame may be included. In addition, as common controlinformation, information related to a length of a CP of the uplink PPDUtransmitted in response to the corresponding trigger frame orinformation related to a length of an LTF field may be included.

In addition, per user information fields 1160 #1 to 1160 #Ncorresponding to the number of receiving STAs which receive the triggerframe of FIG. 6 are preferably included. The per user information fieldmay also be called an “allocation field”.

In addition, the trigger frame of FIG. 6 may include a padding field1170 and a frame check sequence field 1180.

Each of the per user information fields 1160 #1 to 1160 #N shown in FIG.6 may include a plurality of subfields.

FIG. 7 illustrates an example of a common information field of a triggerframe. A subfield of FIG. 7 may be partially omitted, and an extrasubfield may be added. In addition, a length of each subfieldillustrated may be changed.

A length field 1210 illustrated has the same value as a length field ofan L-SIG field of an uplink PPDU transmitted in response to acorresponding trigger frame, and a length field of the L-SIG field ofthe uplink PPDU indicates a length of the uplink PPDU. As a result, thelength field 1210 of the trigger frame may be used to indicate thelength of the corresponding uplink PPDU.

In addition, a cascade identifier field 1220 indicates whether a cascadeoperation is performed. The cascade operation implies that downlink MUtransmission and uplink MU transmission are performed together in thesame TXOP. That is, it implies that downlink MU transmission isperformed and thereafter uplink MU transmission is performed after apre-set time (e.g., SIFS). During the cascade operation, only onetransmitting device (e.g., AP) may perform downlink communication, and aplurality of transmitting devices (e.g., non-APs) may perform uplinkcommunication.

A CS request field 1230 indicates whether a wireless medium state or aNAV or the like is necessarily considered in a situation where areceiving device which has received a corresponding trigger frametransmits a corresponding uplink PPDU.

An HE-SIG-A information field 1240 may include information forcontrolling content of a SIG-A field (i.e., HE-SIG-A field) of theuplink PPDU in response to the corresponding trigger frame.

A CP and LTF type field 1250 may include information related to a CPlength and LTF length of the uplink PPDU transmitted in response to thecorresponding trigger frame. A trigger type field 1260 may indicate apurpose of using the corresponding trigger frame, for example, typicaltriggering, triggering for beamforming, a request for block ACK/NACK, orthe like.

It may be assumed that the trigger type field 1260 of the trigger framein the present specification indicates a trigger frame of a basic typefor typical triggering. For example, the trigger frame of the basic typemay be referred to as a basic trigger frame.

FIG. 8 illustrates an example of a subfield included in a per userinformation field. A user information field 1300 of FIG. 8 may beunderstood as any one of the per user information fields 1160 #1 to 1160#N mentioned above with reference to FIG. 6 . A subfield included in theuser information field 1300 of FIG. 8 may be partially omitted, and anextra subfield may be added. In addition, a length of each subfieldillustrated may be changed.

A user identifier field 1310 of FIG. 8 indicates an identifier of a STA(i.e., receiving STA) corresponding to per user information. An exampleof the identifier may be the entirety or part of an associationidentifier (AID) value of the receiving STA.

In addition, an RU allocation field 1320 may be included. That is, whenthe receiving STA identified through the user identifier field 1310transmits a TB PPDU in response to the trigger frame, the TB PPDU istransmitted through an RU indicated by the RU allocation field 1320.

The subfield of FIG. 8 may include a coding type field 1330. The codingtype field 1330 may indicate a coding type of the TB PPDU. For example,when BCC coding is applied to the TB PPDU, the coding type field 1330may be set to ‘1’, and when LDPC coding is applied, the coding typefield 1330 may be set to ‘0’.

In addition, the subfield of FIG. 8 may include an MCS field 1340. TheMCS field 1340 may indicate an MCS scheme applied to the TB PPDU. Forexample, when BCC coding is applied to the TB PPDU, the coding typefield 1330 may be set to ‘1’, and when LDPC coding is applied, thecoding type field 1330 may be set to ‘0’.

Hereinafter, a UL OFDMA-based random access (UORA) scheme will bedescribed.

FIG. 9 describes a technical feature of the UORA scheme.

A transmitting STA (e.g., an AP) may allocate six RU resources through atrigger frame as shown in FIG. 9 . Specifically, the AP may allocate a1st RU resource (AID 0, RU 1), a 2nd RU resource (AID 0, RU 2), a 3rd RUresource (AID 0, RU 3), a 4th RU resource (AID 2045, RU 4), a 5th RUresource (AID 2045, RU 5), and a 6th RU resource (AID 3, RU 6).Information related to the AID 0, AID 3, or AID 2045 may be included,for example, in the user identifier field 1310 of FIG. 8 . Informationrelated to the RU 1 to RU 6 may be included, for example, in the RUallocation field 1320 of FIG. 8 . AID=0 may imply a UORA resource for anassociated STA, and AID=2045 may imply a UORA resource for anun-associated STA. Accordingly, the 1st to 3rd RU resources of FIG. 9may be used as a UORA resource for the associated STA, the 4th and 5thRU resources of FIG. 9 may be used as a UORA resource for theun-associated STA, and the 6th RU resource of FIG. 9 may be used as atypical resource for UL MU.

In the example of FIG. 9 , an OFDMA random access backoff (OBO) of aSTA1 is decreased to 0, and the STA1 randomly selects the 2nd RUresource (AID 0, RU 2). In addition, since an OBO counter of a STA2/3 isgreater than 0, an uplink resource is not allocated to the STA2/3. Inaddition, regarding a STA4 in FIG. 9 , since an AID (e.g., AID=3) of theSTA4 is included in a trigger frame, a resource of the RU 6 is allocatedwithout backoff.

Specifically, since the STA1 of FIG. 9 is an associated STA, the totalnumber of eligible RA RUs for the STA1 is 3 (RU 1, RU 2, and RU 3), andthus the STA1 decreases an OBO counter by 3 so that the OBO counterbecomes 0. In addition, since the STA2 of FIG. 9 is an associated STA,the total number of eligible RA RUs for the STA2 is 3 (RU 1, RU 2, andRU 3), and thus the STA2 decreases the OBO counter by 3 but the OBOcounter is greater than 0. In addition, since the STA3 of FIG. 9 is anun-associated STA, the total number of eligible RA RUs for the STA3 is 2(RU 4, RU 5), and thus the STA3 decreases the OBO counter by 2 but theOBO counter is greater than 0.

Hereinafter, a PPDU transmitted/received in a STA of the presentspecification will be described.

FIG. 10 illustrates an example of a PPDU used in the presentspecification.

The PPDU of FIG. 10 may be called in various terms such as an EHT PPDU,a TX PPDU, an RX PPDU, a first type or N-th type PPDU, or the like. Forexample, in the present specification, the PPDU or the EHT PPDU may becalled in various terms such as a TX PPDU, a RX PPDU, a first type orN-th type PPDU, or the like. In addition, the EHT PPDU may be used in anEHT system and/or a new WLAN system enhanced from the EHT system.

The PPDU of FIG. 10 may indicate the entirety or part of a PPDU typeused in the EHT system. For example, the example of FIG. 10 may be usedfor both of a single-user (SU) mode and a multi-user (MU) mode. In otherwords, the PPDU of FIG. 10 may be a PPDU for one receiving STA or aplurality of receiving STAs. When the PPDU of FIG. 10 is used for atrigger-based (TB) mode, the EHT-SIG of FIG. 10 may be omitted. In otherwords, an STA which has received a trigger frame for uplink-MU (UL-MU)may transmit the PPDU in which the EHT-SIG is omitted in the example ofFIG. 10 .

In FIG. 10 , an L-STF to an EHT-LTF may be called a preamble or aphysical preamble, and may begenerated/transmitted/received/obtained/decoded in a physical layer.

A subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, andEHT-SIG fields of FIG. 10 may be determined as 312.5 kHz, and asubcarrier spacing of the EHT-STF, EHT-LTF, and Data fields may bedetermined as 78.125 kHz. That is, a tone index (or subcarrier index) ofthe L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields may beexpressed in unit of 312.5 kHz, and a tone index (or subcarrier index)of the EHT-STF, EHT-LTF, and Data fields may be expressed in unit of78.125 kHz.

In the PPDU of FIG. 10 , the L-LTE and the L-STF may be the same asthose in the conventional fields.

The L-SIG field of FIG. 10 may include, for example, bit information of24 bits. For example, the 24-bit information may include a rate field of4 bits, a reserved bit of 1 bit, a length field of 12 bits, a parity bitof 1 bit, and a tail bit of 6 bits. For example, the length field of 12bits may include information related to a length or time duration of aPPDU. For example, the length field of 12 bits may be determined basedon a type of the PPDU. For example, when the PPDU is a non-HT, HT, VHTPPDU or an EHT PPDU, a value of the length field may be determined as amultiple of 3. For example, when the PPDU is an HE PPDU, the value ofthe length field may be determined as “a multiple of 3”+1 or “a multipleof 3”+2. In other words, for the non-HT, HT, VHT PPDI or the EHT PPDU,the value of the length field may be determined as a multiple of 3, andfor the HE PPDU, the value of the length field may be determined as “amultiple of 3”+1 or “a multiple of 3”+2.

For example, the transmitting STA may apply BCC encoding based on a 1/2coding rate to the 24-bit information of the L-SIG field. Thereafter,the transmitting STA may obtain a BCC coding bit of 48 bits. BPSKmodulation may be applied to the 48-bit coding bit, thereby generating48 BPSK symbols. The transmitting STA may map the 48 BPSK symbols topositions except for a pilot subcarrier{subcarrier index −21, −7, +7,+21} and a DC subcarrier {subcarrier index 0}. As a result, the 48 BPSKsymbols may be mapped to subcarrier indices −26 to −22, −20 to −8, −6 to−1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA mayadditionally map a signal of {−1, −1, −1, 1} to a subcarrier index{−28,−27, +27, +28}. The aforementioned signal may be used for channelestimation on a frequency domain corresponding to {−28, −27, +27, +28}.

The transmitting STA may generate an RL-SIG generated in the same manneras the L-SIG. BPSK modulation may be applied to the RL-SIG. Thereceiving STA may know that the RX PPDU is the HE PPDU or the EHT PPDU,based on the presence of the RL-SIG.

A universal SIG (U-SIG) may be inserted after the RL-SIG of FIG. 10 .The U-SIB may be called in various terms such as a first SIG field, afirst SIG, a first type SIG, a control signal, a control signal field, afirst (type) control signal, or the like.

The U-SIG may include information of N bits, and may include informationfor identifying a type of the EHT PPDU. For example, the U-SIG may beconfigured based on two symbols (e.g., two contiguous OFDM symbols).Each symbol (e.g., OFDM symbol) for the U-SIG may have a duration of 4μs. Each symbol of the U-SIG may be used to transmit the 26-bitinformation. For example, each symbol of the U-SIG may betransmitted/received based on 52 data tomes and 4 pilot tones.

Through the U-SIG (or U-SIG field), for example, A-bit information(e.g., 52 un-coded bits) may be transmitted. A first symbol of the U-SIGmay transmit first X-bit information (e.g., 26 un-coded bits) of theA-bit information, and a second symbol of the U-SIB may transmit theremaining Y-bit information (e.g. 26 un-coded bits) of the A-bitinformation. For example, the transmitting STA may obtain 26 un-codedbits included in each U-SIG symbol. The transmitting STA may performconvolutional encoding (i.e., BCC encoding) based on a rate of R=1/2 togenerate 52-coded bits, and may perform interleaving on the 52-codedbits. The transmitting STA may perform BPSK modulation on theinterleaved 52-coded bits to generate 52 BPSK symbols to be allocated toeach U-SIG symbol. One U-SIG symbol may be transmitted based on 65 tones(subcarriers) from a subcarrier index −28 to a subcarrier index +28,except for a DC index 0. The 52 BPSK symbols generated by thetransmitting STA may be transmitted based on the remaining tones(subcarriers) except for pilot tones, i.e., tones −21, −7, +7, +21.

For example, the A-bit information (e.g., 52 un-coded bits) generated bythe U-SIG may include a CRC field (e.g., a field having a length of 4bits) and a tail field (e.g., a field having a length of 6 bits). TheCRC field and the tail field may be transmitted through the secondsymbol of the U-SIG. The CRC field may be generated based on 26 bitsallocated to the first symbol of the U-SIG and the remaining 16 bitsexcept for the CRC/tail fields in the second symbol, and may begenerated based on the conventional CRC calculation algorithm. Inaddition, the tail field may be used to terminate trellis of aconvolutional decoder, and may be set to, for example, “000000”.

The A-bit information (e.g., 52 un-coded bits) transmitted by the U-SIG(or U-SIG field) may be divided into version-independent bits andversion-dependent bits. For example, the version-independent bits mayhave a fixed or variable size. For example, the version-independent bitsmay be allocated only to the first symbol of the U-SIG, or theversion-independent bits may be allocated to both of the first andsecond symbols of the U-SIG. For example, the version-independent bitsand the version-dependent bits may be called in various terms such as afirst control bit, a second control bit, or the like.

For example, the version-independent bits of the U-SIG may include a PHYversion identifier of 3 bits. For example, the PHY version identifier of3 bits may include information related to a PHY version of a TX/RX PPDU.For example, a first value of the PHY version identifier of 3 bits mayindicate that the TX/RX PPDU is an EHT PPDU. In other words, when thetransmitting STA transmits the EHT PPDU, the PHY version identifier of 3bits may be set to a first value. In other words, the receiving STA maydetermine that the RX PPDU is the EHT PPDU, based on the PHY versionidentifier having the first value.

For example, the version-independent bits of the U-SIG may include aUL/DL flag field of 1 bit. A first value of the UL/DL flag field of 1bit relates to UL communication, and a second value of the UL/DL flagfield relates to DL communication.

For example, the version-independent bits of the U-SIG may includeinformation related to a TXOP length and information related to a BSScolor ID.

For example, when the EHT PPDU is divided into various types (e.g.,various types such as an EHT PPDU related to an SU mode, an EHT PPDUrelated to a MU mode, an EHT PPDU related to a TB mode, an EHT PPDUrelated to extended range transmission, or the like), informationrelated to the type of the EHT PPDU may be included in theversion-dependent bits of the U-SIG.

For example, the U-SIG may include: 1) a bandwidth field includinginformation related to a bandwidth; 2) a field including informationrelated to an MCS scheme applied to EHT-SIG; 3) an indication fieldincluding information regarding whether a dual subcarrier modulation(DCM) scheme is applied to EHT-SIG; 4) a field including informationrelated to the number of symbol used for EHT-SIG; 5) a field includinginformation regarding whether the EHT-SIG is generated across a fullband; 6) a field including information related to a type of EHT-LTF/STF;and 7) information related to a field indicating an EHT-LTF length and aCP length.

In the following example, a signal represented as a (TX/RX/UL/DL)signal, a (TX/RX/UL/DL) frame, a (TX/RX/UL/DL) packet, a (TX/RX/UL/DL)data unit, (TX/RX/UL/DL) data, or the like may be a signaltransmitted/received based on the PPDU of FIG. 10 . The PPDU of FIG. 10may be used to transmit/receive frames of various types. For example,the PPDU of FIG. 10 may be used for a control frame. An example of thecontrol frame may include a request to send (RTS), a clear to send(CTS), a power save-poll (PS-poll), BlockACKReq, BlockAck, a null datapacket (NDP) announcement, and a trigger frame. For example, the PPDU ofFIG. 10 may be used for a management frame. An example of the managementframe may include a beacon frame, a (re-)association request frame, a(re-)association response frame, a probe request frame, and a proberesponse frame. For example, the PPDU of FIG. 10 may be used for a dataframe. For example, the PPDU of FIG. 10 may be used to simultaneouslytransmit at least two or more of the control frames, the managementframe, and the data frame.

FIG. 11 illustrates an example of a modified transmission device and/orreceiving device of the present specification.

Each device/STA of the sub-figure (a)/(b) of FIG. 1 may be modified asshown in FIG. 11 . A transceiver 630 of FIG. 11 may be identical to thetransceivers 113 and 123 of FIG. 1 . The transceiver 630 of FIG. 11 mayinclude a receiver and a transmitter.

A processor 610 of FIG. 11 may be identical to the processors 111 and121 of FIG. 1 . Alternatively, the processor 610 of FIG. 11 may beidentical to the processing chips 114 and 124 of FIG. 1 .

A memory 620 of FIG. 11 may be identical to the memories 112 and 122 ofFIG. 1 . Alternatively, the memory 620 of FIG. 11 may be a separateexternal memory different from the memories 112 and 122 of FIG. 1 .

Referring to FIG. 11 , a power management module 611 manages power forthe processor 610 and/or the transceiver 630. A battery 612 suppliespower to the power management module 611. A display 613 outputs a resultprocessed by the processor 610. A keypad 614 receives inputs to be usedby the processor 610. The keypad 614 may be displayed on the display613. A SIM card 615 may be an integrated circuit which is used tosecurely store an international mobile subscriber identity (IMSI) andits related key, which are used to identify and authenticate subscriberson mobile telephony devices such as mobile phones and computers.

Referring to FIG. 11 , a speaker 640 may output a result related to asound processed by the processor 610. A microphone 641 may receive aninput related to a sound to be used by the processor 610.

Hereinafter, technical features of multi-link (ML) supported by the STAof the present specification will be described.

STAs (AP and/or non-AP STA) of the present specification may supportmulti-link (ML) communication. ML communication may mean communicationsupporting a plurality of links. Links related to ML communication mayinclude channels (e.g., 20/40/80/160/240/320 MHz channels) of the 2.4GHz band, the 5 GHz band, and the 6 GHz band.

A plurality of links used for ML communication may be set in variousways. For example, a plurality of links supported by one STA for MLcommunication may be a plurality of channels in the 2.4 GHz band, aplurality of channels in the 5 GHz band, and a plurality of channels inthe 6 GHz band. Alternatively, a plurality of links may be a combinationof at least one channel within the 2.4 GHz band (or 5 GHz/6 GHz band)and at least one channel within the 5 GHz band (or 2.4 GHz/6 GHz band).Meanwhile, at least one of a plurality of links supported by one STA forML communication may be a channel to which preamble puncturing isapplied.

The STA may perform ML setup to perform ML communication. ML setup maybe performed based on management frames or control frames such asBeacon, Probe Request/Response, and Association Request/Response. Forexample, information on ML setup may be included in element fieldsincluded in Beacon, Probe Request/Response, and AssociationRequest/Response.

When ML setup is completed, an enabled link for ML communication may bedetermined. The STA may perform frame exchange through at least one of aplurality of links determined as an enabled link. For example, anenabled link may be used for at least one of a management frame, acontrol frame, and a data frame.

When one STA supports a plurality of Links, a transmitting/receivingdevice supporting each Link may operate like one logical STA. Forexample, one STA supporting two links may be expressed as one ML device(Multi Link Device; MLD) including a first STA for a first link and asecond STA for a second link. For example, one AP supporting two linksmay be expressed as one AP MLD including a first AP for a first link anda second AP for a second link. In addition, one non-AP supporting twolinks may be expressed as one non-AP MLD including a first STA for thefirst link and a second STA for the second link.

More specific features of the ML setup are described below.

An MLD (AP MLD and/or non-AP MLD) may transmit information about a linkthat the corresponding MLD can support through ML setup. Link-relatedinformation may be configured in various ways. For example, link-relatedinformation includes at least one of 1) information on whether the MLD(or STA) supports simultaneous RX/TX operation, 2) information on thenumber/upper limit of uplink/downlink links supported by the MLD (orSTA), 3) information on the location/band/resource of uplink/downlinklink supported by MLD (or STA), 4) type of frame available or preferredin at least one uplink/downlink link (management, control, data etc.),5) available or preferred ACK policy information on at least oneuplink/downlink link, and 6) information on available or preferred TID(traffic identifier) on at least one uplink/downlink link. The TID isrelated to the priority of traffic data and is represented by 8 types ofvalues according to the conventional wireless LAN standard. That is, 8TID values corresponding to 4 access categories (AC) (AC_BK(background), AC_BE (best effort), AC_VI (video), AC_VO (voice))according to the conventional wireless LAN standard may be defined.

For example, it may be set in advance that all TIDs are mapped foruplink/downlink links. Specifically, if negotiation is not done throughML setup, all TIDs may be used for ML communication, and if mappingbetween uplink/downlink links and TIDs is negotiated through additionalML setup, the negotiated TIDs may be used for ML communication.

A plurality of links that can be used by the transmitting MLD and thereceiving MLD related to ML communication can be set through ML setup,and this can be called an enabled link. The enabled link can be calleddifferently in a variety of ways. For example, it may be called variousexpressions such as a first link, a second link, a transmitting link,and a receiving link.

After the ML setup is complete, the MLD may update the ML setup. Forexample, the MLD may transmit information about a new link when updatinginformation about a link is required. Information about the new link maybe transmitted based on at least one of a management frame, a controlframe, and a data frame.

The device described below may be the apparatus of FIGS. 1 and/or 11 ,and the PPDU may be the PPDU of FIG. 10 . A device may be an AP or anon-AP STA. A device described below may be an AP multi-link device(MLD) or a non-AP STA MLD supporting multi-link.

In EHT (extremely high throughput), a standard being discussed after802.11ax, a multi-link environment in which one or more bands aresimultaneously used is considered. When a device supports multi-link,the device can simultaneously or alternately use one or more bands(e.g., 2.4 GHz, 5 GHz, 6 GHz, 60 GHz, etc.).

In the following specification, MLD means a multi-link device. The MLDhas one or more connected STAs and has one MAC service access point(SAP) that communicates with the upper link layer (Logical Link Control,LLC). MLD may mean a physical device or a logical device. Hereinafter, adevice may mean an MLD.

In the following specification, a transmitting device and a receivingdevice may mean MLD. The first link of the receiving/transmitting devicemay be a terminal (e.g., STA or AP) included in thereceiving/transmitting device and performing signaltransmission/reception through the first link. The second link of thereceiving/transmitting device may be a terminal (e.g., STA or AP) thattransmits/receives a signal through the second link included in thereceiving/transmitting device.

In IEEE802.11be, two types of multi-link operations can be supported.For example, simultaneous transmit and receive (STR) and non-STRoperations may be considered. For example, STR may be referred to asasynchronous multi-link operation, and non-STR may be referred to assynchronous multi-link operation. Multi-links may include multi-bands.That is, multi-links may mean links included in several frequency bandsor may mean multiple links included in one frequency band.

EHT (11be) considers multi-link technology, where multi-link may includemulti-band. That is, multi-link can represent links of several bands andmultiple multi-links within one band at the same time. Two majormulti-link operations are being considered. Asynchronous operation,which enables TX/RX simultaneously on several links, and synchronousoperation, which is not possible, are being considered. Hereinafter, acapability that enables simultaneous reception and transmission onmultiple links is referred to as STR (simultaneous transmit andreceive), an STA having STR capability is referred to as STR MLD(multi-link device), and an STA that does not have STR capability isreferred to as a non-STR MLD.

In the following specification, for convenience of explanation, it isdescribed that the MLD (or the processor of the MLD) controls at leastone STA, but is not limited thereto. As described above, the at leastone STA may transmit and receive signals independently regardless ofMLD.

According to an embodiment, an AP MLD or a non-AP MLD may have astructure having a plurality of links. In other words, a non-AP MLD cansupport multiple links. A non-AP MLD may include a plurality of STAs. Aplurality of STAs may have Link for each STA.

In the EHT standard (802.11be standard), the MLD (Multi-Link Device)structure in which one AP/non-AP MLD supports multiple links isconsidered as a major technology. STAs included in the non-AP MLD maytransmit information about other STAs in the non-AP MLD together throughone link. Accordingly, there is an effect of reducing the overhead offrame exchange. In addition, there is an effect of increasing the linkuse efficiency of the STA and reducing power consumption.

FIG. 12 shows an example of a structure of a non-AP MLD.

Referring to FIG. 12 , a non-AP MLD may be configured with a pluralityof links. In other words, a non-AP MLD can support multiple links. Anon-AP MLD may include a plurality of STAs. A plurality of STAs may haveLink for each STA. Although FIG. 12 shows an example of a non-AP MLDstructure, the structure of the AP MLD may also be configuredidentically to the example of the structure of the non-AP MLD shown inFIG. 12 .

For example, the non-AP MLD may include STA 1, STA 2, and STA 3. STA 1can operate on link 1. link 1 may be included in the 5 GHz band. STA 2can operate on link 2. link 2 may be included in the 6 GHz band. STA 3can operate on link 3. link 3 may be included in the 6 GHz band. Bandsincluded in link 1/2/3 are exemplary and may be included in 2.4, 5, and6 GHz.

As such, in the case of an AP/non-AP MLD supporting multi-link, each APof the AP MLD and each STA of the non-AP MLD may be connected to eachlink through a link setup process. And at this time, the connected linkcan be changed or reconnected to another link by AP MLD or non-AP MLDdepending on the situation.

In addition, in the EHT standard, a link may be classified as ananchored link or a non-anchored link in order to reduce powerconsumption. An anchored link or non-anchored link can be calledvariously. For example, an anchored link may be referred to as a primarylink. A non-Anchored Link can be called a Secondary link.

According to an embodiment, an AP MLD supporting multi-link can bemanaged by designating each link as an anchored link or a non-anchoredlink. The AP MLD may support one or more links among a plurality oflinks as an anchored link. A non-AP MLD can use it by selecting one ormore of its own anchored links from the Anchored Link List (list ofanchored links supported by the AP MLD).

For example, Anchored Link can be used for non-data frame exchange (i.e.Beacon and Management frame) as well as frame exchange forsynchronization. Also, non-anchored links can only be used for dataframe exchange.

The non-AP MLD can monitor only the anchored link for receiving beaconsand management frames during the idle period. Therefore, in the case ofnon-AP MLD, at least one anchored link must be connected to receivebeacon and management frame. The one or more Anchored Links must alwaysmaintain an enable state. In contrast, non-anchored links are used onlyfor data frame exchange. Accordingly, an STA corresponding to anon-anchored link (or an STA connected to a non-anchored link) may enterdoze during an idle period not using a channel/link. This has the effectof reducing power consumption.

Therefore, in the following specification, a protocol for recommendingor requesting link reconnection by an AP MLD or a non-AP MLD dynamicallyaccording to circumstances may be proposed for efficient linkconnection. In addition, in the following specification, an anchoredlink reconnection protocol considering characteristics of an anchoredlink used for the purpose of power reduction as well as a general linkmay be additionally proposed.

Example for Link Change and Reconnection

According to an embodiment, each link between an AP MLD and a non-AP MLDmay be determined in an Association or (re)Association process. At thistime, the AP MLD and the non-AP MLD can perform frame exchange throughthe connected Link. A specific embodiment in which an AP MLD and anon-AP MLD are connected through a link setup process can be describedwith reference to FIG. 13 .

FIG. 13 illustrates an example in which an AP MLD and a non-AP MLD areconnected through a link setup process.

Referring to FIG. 13 , the AP MLD may include AP 1, AP 2, and AP 3. Thenon-AP MLD may include STA 1 and STA 2. AP 1 and STA 1 may be connectedthrough link 1. AP 2 and STA 2 may be connected through link 2.

For example, AP 1 and STA 1 may be connected through link 1 through afirst link setup process. AP 2 and STA 2 may be connected through link 2through a second link setup process. For another example, AP MLD andnon-AP MLD may be connected through a one-time link setup process. Inother words, the AP MLD and the non-AP MLD may be connected through link1 and link 2 based on a link setup process once.

As described above, each AP and STA may perform frame exchange throughthe connected Link. In addition, information of other APs on a differentlink or other STAs on a different link may be transmitted and receivedthrough one link.

However, after this link setup process, the AP MLD or non-AP MLD mayrequest link change or reconnection for more efficient frame exchange(e.g., load balancing or interference avoiding, etc.) depending on thesituation/environment.

An embodiment of link change or reconnection may be described withreference to FIG. 14 .

FIG. 14 illustrates an example in which Link is changed or reconnected.

Referring to FIG. 14 , conventionally, STA 2 is connected to AP 2.Thereafter, data load of AP 2 may be excessive. STA 2 may be reconnectedto AP 3 having a relatively small data load. In this case, there is aneffect that the AP MLD and the non-AP MLD can perform efficient dataexchange.

FIG. 15 illustrates a specific example in which Link is changed orreconnected.

Referring to FIG. 15 , AP 1 of the AP MLD may be connected to STA 1 ofthe non-AP MLD through link 1. AP 2 of the AP MLD may be connected toSTA 2 of the non-AP MLD through link 2. Thereafter, STA 2 mayattempt/request connection with AP 3 through link change orreconnection, and STA 2 may connect to AP 3 through link 2 based on thelink change or reconnection.

According to an embodiment, the non-AP MLD and the AP MLD may requestlink transition to improve performance. The AP MLD and the non-AP MLDcan transmit/receive/exchange various information and link stateinformation for each current link. Therefore, the AP MLD and the non-APMLD can select a link more suitable for transmitting and receivingsignals based on various information and link states for each currentlink, and can transmit the above-described information to help theselection. For example, various types of information for each currentlink may include information about data traffic load for each link andchannel access capability between links. For example, a link state maybe set to disable or enable.

In the following specification, the process of negotiating with thenon-AP MLD/AP MLD to request a change or reconnection to a link otherthan the link to which the AP MLD/non-AP MLD is connected to improveperformance may be referred to as “Link switching negotiation”. The nameof the “Link switching negotiation” may be called variously, and may bechanged.

In the link switching negotiation process, the non-AP MLD (or AP MLD)requests to change the Link connected to a specific STA to another Link,the AP MLD (or non-AP MLD) may respond to this request through a requestacceptance or rejection message.

For example, as shown in FIG. 15 , when link change is agreed uponthrough link switching negotiation, the STA may perform a link re-setupprocess in which the existing link is changed from AP 2 to AP 3 andreconnected.

Hereinafter, a link change or reconnection process can be described bydividing into a case requested by an AP MLD and a case requested by anon-AP MLD.

An Embodiment in which the AP MLD Requests Link Change or Reconnection

According to an embodiment, the AP MLD may request link change orreconnection from the non-AP MLD for efficient data transmission. Forexample, based on data traffic of each AP for load balancing, the AP MLDmay request the STA to change or reconnect to a more efficient link.

For example, AP MLD is non-AP MLD based on data traffic load informationfor each AP and/or channel access capability information between eachlink (e.g., Simultaneous TX/RX (STR) capability information, etc.) Linkssuitable for STAs of can be calculated/confirmed/confirmed. Thereafter,the AP MLD may request link change or reconnection to the STA (or non-APMLD) based on data traffic load information for each AP and/or channelaccess capability information between each link.

As described above, when requesting a Link change, the AP MLD maytransmit Link information it considers most suitable to the non-AP MLDthrough a request message. For example, the request message may includea Beacon or a management frame.

In relation to the above-described embodiment, an element or fieldincluding link information that is considered most suitable may be newlyproposed. A newly proposed element or field may be defined as a“recommended link”. “Recommended link” is an example, and the name of aspecific element or field may be changed.

recommend link (element/field): An element or field for the AP MLD torecommend the most suitable Link to the STA of the non-AP MLD based onvarious information (e.g., data load for each Link) for each Link. Forexample, recommend link (element/field) may be indicated by Link IDinformation of AP MLD or AP BSS information. In other words, therecommend link (element/field) may include AP MLD Link ID information orAP BSS information.

According to one embodiment, the recommend link (element/field) mayoptionally be included in a link switching response and transmitted. Forexample, the STA may establish a connection with the Link recommended bythe AP based on the element/field (i.e., recommend Link). For anotherexample, the STA may perform a connection request to a Link differentfrom the indicated Link based on the element/field (i.e., recommendLink) and additional information possessed by the STA.

A detailed signal exchange process between an AP MLD and a non-AP MLDaccording to the above-described embodiment may be described withreference to FIG. 16 .

FIG. 16 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

Referring to FIG. 16 , in a situation in which STA 2 is connected to AP2 through link 2, a lot of data traffic may flow to AP 2. In otherwords, in a situation where STA 2 is connected to AP 2 through link 2, alot of data traffic may be generated in AP 2.

The AP MLD (or AP 2) may request the non-AP MLD (or STA 2) to reconnectto AP 3 having relatively few STA connections. In general, a message forrequesting reconnection is transmitted to the STA (i.e., STA 2) thatwants to reconnect, but depending on the situation (e.g., channel statusor link status), the message may be transmitted to any STA (i.e., otherSTA). In other words, based on the channel condition or link condition,the STA to which the request message for requesting reconnection (e.g.,Link switching request frame) is transmitted may be changed.

For example, when the STA (i.e., STA 2) receiving the request messagefor requesting reconnection accepts the request, an “Accept” responsemessage (e.g., Link switching response frame) may be sent. For anotherexample, the STA (i.e., STA 2) may transmit a “Decline” response messagewhen rejecting the request.

In general, the STA accepting reconnection (i.e., STA 2) sends aresponse message to the existing link (connection link prior toreconnection), the response message may be transmitted through any Link(i.e., another STA) using the multi-link characteristic.

If STA 2 accepts the link reconnection request, after transmitting theresponse message, STA 2 may disconnect from the existing AP 2 andrequest link reconnection to AP 3. At this time, the reconnectionrequest process may be performed in the same way as the link setupprocess between existing MLDs. After the link setup process between AP 3and STA 2 is completed, STA 2 may perform frame exchange with AP 3through Link 2.

Conversely, when STA 2 rejects the link reconnection request, STA 2 andAP 2 may use the existing linked link (i.e., link 2) as it is.

According to an embodiment, when an AP requests a link change from anSTA, if a suitable link is recommended, the STA may or may not changethe link to the recommended link. For example, the above-describedrecommend link may be used for the AP to recommend a link suitable forthe STA.

For example, the STA may approve a link change as a response message toa request message for requesting reconnection of the AP. The STA mayapprove/confirm the link change with the recommended link, and mayrequest another link change from the AP based on information other thanthe information included in the request message.

Therefore, the AP needs to inform the STA whether or not to accept theresponse message. To this end, the AP may transmit a Confirmationmessage (e.g., link switching confirmation frame) for the STA's responsemessage (e.g., Link switching Response frame) to the STA.

Specific operations of the AP MLD and non-AP MLD of the above-describedembodiment may be described with reference to FIG. 17 .

FIG. 17 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

Referring to FIG. 17 , AP 2 may request link change from STA 2 includingrecommended link information. In other words, AP 2 may transmit a linkswitching request frame including recommended link information to STA 2.

STA 2 may transmit whether to accept the link request through a Linkswitching Response frame.

For example, when Link switching is accepted, STA 2 may transmit Linkswitching response frame including Link information to be changed. Atthis time, Link information to be changed may or may not be the same asthe recommended link.

For another example, when STA 2 selects a link other than therecommended link provided by AP 2 and responds with a link switchingresponse frame, the AP may transmit a message on whether or not toapprove the final to the STA. The message may be referred to as a Linkswitching confirmation frame.

For example, AP 2 may accept link change to a link designated by STA 2through a Link switching Confirmation frame. Based on the Link switchingConfirmation frame, STA 2 may attempt to change the link to a linkdesignated by itself.

As another example, AP 2 may reject link change to a link designated bySTA 2 through a Link switching Confirmation frame. STA 2 and AP 2 canmaintain a connection with an existing Link without changing the link.

The embodiment shown in FIG. 17 can be applied even when the APtransmits the link switching request frame without including recommendedlink information. For example, when an AP (e.g., AP 2) transmits a Linkswitching request frame without recommendation link information to anSTA (e.g., STA 2), the STA may directly designate a changed Link basedon its own information, and then respond to the AP through a Linkswitching response frame. Even in this case, the AP must finallytransmit a Link switching Confirmation frame for approval. Therefore, anembodiment in which the AP transmits a Link switching Confirmation frameeven when the recommended link information is not included in the Linkswitching request frame may be applied.

An Embodiment in which a Non-AP MLD Requests Link Change or Reconnection

According to an embodiment, the non-AP MLD may request link change orreconnection to the AP MLD for efficient data transmission. For example,in order to use the STR capability during data transmission, the non-APMLD may request connection link change or reconnection from the AP MLD.

FIG. 18 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

Referring to FIG. 18 , an AP MLD and a non-AP MLD may perform linkswitching negotiation. STA 2 of the non-AP MLD may transmit a linkswitching request frame to AP 2 of the AP MLD. AP 2 of the AP MLD maytransmit a link switching response frame to STA 2 of the non-AP MLD inresponse to the link switching request frame. The link switching requestframe or link switching response frame may be transmitted and receivedthrough a link to be changed, but is not limited thereto. A linkswitching request frame or a link switching response frame may betransmitted and received through various links as well as a link to bechanged.

The non-AP MLD may request link change or reconnection through variousmethods. Hereinafter, three methods for non-AP MLD to request linkchange or reconnection may be proposed. Specifically, the above threemethods can be sequentially described as a solicited method, anunsolicited method, and a general method.

1) Solicited method: A method in which a non-AP MLD requests variousinformation for Link (re)selection from the AP MLD and receives variousinformation through this. For example, various pieces of information mayinclude information about capabilities, operation elements, and BSSparameters.

According to an embodiment, a method in which an STA requestsinformation of other APs of a connected AP MLD may be used in variouscases, not only when a link is reconfigured. For example, aftermulti-link setup, the STA may request BSS parameter information of otherAPs for link switching and select the best link based on the receivedinformation. Alternatively, in the discovery process, the STA mayrequest BSS load information of each AP from the AP MLD and select alink to perform link setup based on the received information. (However,it is assumed that the number of APs in the AP MLD is greater than thenumber of STAs in the non-AP MLD.)

Accordingly, the AP receiving the information request message maytransmit any information such as capability information, BSS parameterinformation, critical parameters, and/or operation element informationfor all APs in the AP MLD. The above-described examples may be appliedto all embodiments described below.

2) Unsolicited method: A method in which the AP transmits variousinformation for Link (re)selection without a separate informationrequest from the non-AP MLD. The STA may utilize the receivedinformation in various situations. According to an embodiment, a methodin which an AP of an AP MLD transmits information of other APs without arequest for separate information from an STA may be used in variouscases as well as when a link is reconfigured. Accordingly, the APreceiving the information request message may transmit any informationsuch as capability information, BSS parameter information, criticalparameters, and/or operation element information for all APs in the APMLD. The above-described examples may be applied to all embodimentsdescribed below.

3) General method: A method in which a non-AP MLD requests Link(re)selection without additional information based on informationacquired through previous Beacon frames, etc.

1) Solicited Method

Hereinafter, an embodiment of the solicited method described above maybe described first.

According to an embodiment, the non-AP MLD may request information forselecting a suitable link from the AP MLD before link change orreconnection. The STA may utilize data load information for each AP orcapability information of each link (or information of other links) inorder to select an appropriate link.

For example, the capability information for each link may be included ina beacon frame and transmitted periodically.

For another example, capability information for each link is optionalinformation and may not be included in a beacon frame transmitted everyperiod. Alternatively, in order to reduce frame overhead, onlyinformation on a link to which the STA is connected or some links towhich the STA is connected may be received. Alternatively, if the beaconreception period is long due to the nature of the non-AP MLD (e.g.,low-power device), the non-AP MLD may not be able to receive capabilityinformation for each link for more appropriate link selection.

In the above cases, the non-AP MLD may request the latest information ofcapability information for each link and information for each link ofthe AP MLD (e.g., BSS parameter information or operation elementinformation, etc.). The link of the capability information for each linkand the information for each link may include not only atransmitted/received link but also other links. For example, a QoS dataframe field (A-Control field of the 11ax standard), a management frame,a probe response/request frame, a PS-Poll frame, or a null frame may beused to request/transmit the latest information. Alternatively, aseparate new frame may be defined to request/transmit the latestinformation.

According to an embodiment, in order to request capability informationfor each link and latest information for each link of the AP MLD, theSTA may transmit a request message requesting information necessary forlink reselection to the AP. For example, a conventionally defined proberequest frame for the request message may be reused. For anotherexample, a new frame for the request message may be defined.

According to an embodiment, through the request message, the STA mayspecify necessary specific information and request it from the AP.Specific information that can be designated may be changed according tocircumstances. That is, the STA may request only informationcorresponding to a specific link or information corresponding to aspecific capability. For example, information corresponding to aspecific link may include information about BSS load/parameters of thespecific link. Also, information corresponding to capability may includeBSS load information of all links (all links) or BSS load information ofa specific link. In this case, the AP may transmit only informationdesignated by the STA through a response message. A specific embodimentof a specific information request and response may be described throughan embodiment of an IOM definition and operation.

As another example, the STA may request all capability informationcurrently possessed by the AP MLD (e.g., including information on otherlinks) through the request message.

As in the above example, an embodiment for transmitting all informationpossessed by an AP or an embodiment for transmitting only specificinformation designated by an STA may be defined/configured in variousways. For example, the AP may transmit all information or designatedinformation based on a separate field or bitmap to indicate (ortransmit) only specific information.

In general, a message requesting information from the AP MLD may betransmitted through an STA that wants reconnection, but may betransmitted to any STA (i.e., other STA) depending on circumstances(channel condition or link condition).

The AP MLD receiving the request message sends a response message (i.e.,information message) including information requested by the STA (e.g.,data load information for each link, STR capability information betweenlinks, etc.) to the non-AP MLD. there is. For example, when a proberequest frame of a conventional standard is reused for the requestmessage, the AP (or AP MLD) must respond using a probe response frame asthe response message.

The response message may also be generally transmitted through the APthat has received the request message, but may be transmitted to any AP(i.e., other AP) using multi-link characteristics.

Optionally, the AP MLD may transmit a “recommend link” elementrecommending a suitable link to the STA through a response messageincluding various pieces of information (e.g., latest informationnecessary for link reselection).

In this specification, a case where an STA of a non-AP MLD requestsinformation of another AP is defined in detail.

When an STA of a non-AP MLD transmits an MLD Probe request frame torequest complete information of other APs from a peer AP, the peer APresponds with an MLD Probe response frame including complete informationon APs requested by the STA. will be. In this case, the peer AP mayrespond with the entire information about the requested AP to the MLDProbe Response frame as follows.

1-1) when the STA Requests Complete Information on the Other AP, aMethod of Including the Complete Information of the Peer AP as Mandatoryin the MLD Probe Response

This method is a method of putting all information of the peer APtogether even when the STA requests all information of other APs of thesame AP MLD except for the peer AP. Currently, 802.11be uses aninheritance model to reduce the overhead of MLD Probe Response.Therefore, when the STA requests complete information of other APs, ifthe AP always includes the complete information of the peer AP, theinheritance model can be applied. In other words, if the AP MLD includespeer AP information in response to a request for all information aboutspecific APs, the value common within the same MLD is included as commoninfo in the ML I.E., and the information different for each AP is the MLIE Different information can be included for each AP as anon-inheritance element in My Per-STA Profile. When the STA requests allinformation about several other APs, the overhead of the entire MLDProbe response frame can be reduced by composing the same informationwith Common info only once. However, in this case, if the STA does notrequest all information about peer APs, there is some overhead becauseunrequested information about peer APs is also included, but wheninformation about multiple other APs is requested, inheritance model Itcan be useful because the overhead reduced by using can be larger.

1-2) when the STA Requests Complete Information about the Other AP, aMethod of not Including the Entire Information of the Peer AP asMandatory in the MLD Probe Response (i.e., a Method of TransmittingIncluding Only the Entire Information of the Requested Other APs)

In this method, when an STA requests complete information about otherAPs from a peer AP, only entire information about the requested APs isincluded in the MLD Probe response and transmitted. In this method, whenan STA requests information about a peer AP together, overhead can bereduced by applying an inheritance model, if the STA requests onlyinformation about other APs of the same AP MLD, excluding informationabout peer APs, the inheritance model cannot be applied. Therefore, ifthe peer AP information is not included, the inheritance model is notapplied, which may increase the overhead somewhat. When the STA requestscomplete information only for a specific AP rather than multiple APs,overhead may be rather small because unnecessary peer AP information isnot included. It is a method of responding with only the information ofthe APs requested by the STA. Although it may be somewhat simpler thanthe first Mandatory method, as the number of other APs within the sameAP MLD to which the STA requests complete information increases, thefirst mandatory method using the inheritance model may be moreefficient.

1-3) how the Peer AP Transmits the Entire Information by Configuring theSide with Less Overhead Depending on the Case

In the first case according to the configuration of the MLD ProbeResponse frame according to the common info information of the APrequested by the AP by the STA (if the STA does not request informationabout the peer AP together, the method of including the information ofthe peer AP in the response as mandatory) and the second case (when theSTA does not request information about the peer AP together, this methodis a method of constructing and transmitting an MLD Probe Response in anefficient way by comparing frame overhead occurring in a method in whichpeer AP information is not included as mandatory in the response). Inother words, the STA responds by configuring a format with less overheadby comparing the efficiency of applying the inheritance model accordingto the information of the APs requested by the STA. However, in thismethod, the criterion considered to be efficient by comparing the twocases may be determined according to the implementation of the AP.

The method for the various options described above is a method for thecase where the STA requests complete information on other APs, and whenthe STA requests partial information on other APs, it may not applybecause information on a specific IE is requested. However, when the STArequests complete information for some APs and partial information forsome APs in one MLD Probe Request frame, the three methods mentionedabove can be used because the inheritance model can be applied.

The solicited method described above may be used for link change orreconnection in an STA of a non-AP MLD. For example, when an STA of anon-AP MLD wants Link reselection due to Link congestion, the STA of thenon-AP MLD may request BSS load information and BSS parameterinformation for each link of the connected AP MLD through a solicitedmethod. Upon receiving this request message, the AP may transmit thelink and information indicated by the STA in a response message.

Hereinafter, the above-described request message and response messagemay be described as an information request message and an informationresponse message in order to be distinguished from a request message forlink change and a response message for link change.

Based on the information included in the above-described informationresponse message, the STA may reselect an appropriate link and requestlink change or reconnection to the AP MLD through a link change requestmessage. The request message for link change may include AP informationand Link information to be reconnected to.

Upon receiving the request message, the AP MLD may transmit a responsemessage of “Accept” when accepting the request. When the AP MLD rejectsthe request, it may transmit a response message of “Decline”.

If the request is accepted, the AP may perform Link (re)setup based onframe exchange through the Link of the reselected AP after transmittingthe response message. Conversely, when rejecting the request, the STAcan use the existing connected Link as it is.

An example of specific AP MLD and non-AP MLD operations according to thesolicited method may be described through FIG. 19 .

FIG. 19 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

Referring to FIG. 19 , when STA 2 of the non-AP MLD wants to reselect aconnected Link, STA 2 may transmit an Info request message to the AP MLDthrough Link 2. Upon receiving this, the AP MLD may transmit an Inforesponse message including information necessary for link reselection ofthe non-AP MLD. Based on the information included in the above-describedInfo response message, STA 2 of the non-AP MLD may transmit a linkchange request message (i.e., link switching request frame) to AP 2 ofthe AP MLD. Thereafter, STA 2 may receive a response message for linkchange (i.e., link switching request frame) and perform link (re)set-upfor link change.

An embodiment of an information request proposed in this specificationmay be used/applied even when an STA requests necessary information froman AP. When information included in a frame (e.g., beacon) received bythe STA from the AP is insufficient, the STA may request the AP for theinsufficient information. For example, when the AP transmits onlyinformation on a connected link without including information on theother link or transmits information on whether or not information on theother link is updated, the STA may request the AP for insufficientinformation.

A specific example of the above embodiment may be described through FIG.20 .

FIG. 20 illustrates an operation of a non-AP MLD for requestinginformation on other APs.

Referring to FIG. 20 , an AP MLD (or AP 1 to AP 3) may transmit onlyinformation about whether other APs (i.e., links) information is updatedto the STA through a beacon frame. Accordingly, STA 2 may transmit anInfo request message (or Info request frame) to AP 2. STA 2 may receivean Info response message (or Info message) based on the Info requestmessage. STA 2 may receive/obtain information about the other AP basedon the Info response message.

For example, if Beacon does not include other AP information (e.g., BSSload information, etc.) of AP MLD, or information about whether AP 2 hasupdated other AP information (e.g., version/update version) can only betransmitted.

STA 2 may need information about AP 1 (or information about AP 1). STA 2may request necessary information through AP 2. STA 2 may obtaininformation of AP 1 through a response message to the request. STA 2 canuse the information of AP 1 to reselect an appropriate link for linkswitching. For example, frames for link switching can be set in variousways.

Additionally, the above-described solicited method may be used for theSTA to acquire information of APs possessed by the AP MLD even beforemulti-link setup. In the multi-link setup process of non-AP MLD and APMLD, if the number of APs in the AP MLD is greater than the number ofSTAs in the non-AP MLD, STAs of the non-AP MLD must decide which AP ofthe AP MLD to establish a link with. In this case, the STA of the non-APMLD may request link-specific information (e.g., BSS load information ofAPs possessed by the AP MLD, etc.) to the AP of the AP MLD to know thestatus of each link before multi-link setup. For example, the STA mayuse a probe request as a request message. As another example, a newframe for a request message may be defined. The STA may transmit therequest message by including an indicator for requesting a specificelement in the request message (e.g., Request element, Extended Requestelement, PV1 Probe Response Option element, etc.) and an indicator forindicating specific link information (e.g., Link ID, etc.).

For example, an STA of a non-AP MLD may transmit a request messageincluding instructions for requesting current BSS load information forall APs in the AP MLD to be connected. Upon receiving the requestmessage, the AP may transmit necessary information (BSS load informationof all APs of the AP MLD to which the AP is connected) in a responsemessage based on the instructions of the STA to the STA. At this time,the STA checking the BSS load information for each AP may select a linkto be connected in order of the BSS (i.e., AP) having the smallest BSSload. The STA may indicate the selected link during multi-link setup. Inother words, information on a selected link may be transmitted to the APduring multi-link setup.

In this way, the STA may use the above-described solicited method as amethod for acquiring information for each AP of the AP MLD in order toselect a link to be connected before multi-link setup.

Hereinafter, a new element/field including information for an STA of anon-AP MLD to select an appropriate link may be proposed.

For example, “ratio per Link” (element/field) may be suggested. “STAratio per Link” may include information about the ratio of the number ofSTAs connected to each link. Specific details of “STA ratio per Link” Anexample can be described through FIG. 21 .

FIG. 21 shows a specific example of STA ratio per Link.

Referring to FIG. 21 , STA ratio per Link (element/field) may includeinformation about the number or ratio of STAs connected to each link inthe entire AP MLD.

For example, if a total of 50 STAs are connected to an AP MLD with 3Links, 10 STAs can be connected to Link 1 and 20 STAs can be connectedto Link 2. The AP MLD may transmit information about a value or ratio(%) of information about an STA connected to each Link to a non-AP MLDthrough STA ratio per Link (element/field).

For example, when information about an STA connected to each Link isexpressed as a value, Link 1 may be expressed/set as 10 and Link 2 as20. Accordingly, the value of STA ratio per link 1 may be set to 10. Inaddition, the value of STA ratio per link 2 may be set to 20.

As another example, when information on STAs connected to each Link isexpressed as a ratio, Link 1 may be expressed/set as 20 (10/50)% andLink 2 as 40 (20/50)%. Accordingly, the value of STA ratio per link 1may be set to 20. In addition, the value of STA ratio per link 2 may beset to 40.

The above example is illustrative, and information on STAs connected toeach link can be set in various ways. In addition to the above examples,information on STAs connected to each link may be set as a relativevalue.

Based on the information about the STAs connected to each link describedabove, the STA can check/acquire the number and ratio of STAs connectedto each link, and can use this as information for link selection.

According to one embodiment, various information/element/fields may beincluded in the information response message in addition to theabove-described “ratio per Link” (element/field). For example, thefollowing information/element/field may be included in the informationresponse message can be included in

-   -   BSS load information for each AP    -   STR Capability information between Links    -   TXOP information for each link    -   NAV information for each link    -   Recommended Link information (i.e. “recommend Link” element)    -   Link-specific STA ratio information (i.e., “STA ratio per Link”        element)    -   Etc.

In addition to the information/element/field described above, variousinformation required for link selection may be included in theinformation response message and transmitted.

Upon receiving information such as the above example, the STA may selectan AP to be changed or reconnected to based on the received information,and then transmit a request message for requesting link reconnection.Upon receiving the request message, the AP MLD may transmit a responsemessage of “Accept” when accepting the request. When the AP MLD rejectsthe request, it may transmit a response message of “Decline”.

If the request is accepted, the AP can perform frame exchange throughthe link with the reselected AP after sending the response message.Conversely, in case of rejection, the STA can use the existing linkedLink as it is.

2) Unsolicited Method

Unlike the solicited method in which the non-AP MLD directly requestsadditional information, according to the unsolicited method, a beaconframe or a separate frame (e.g., a field of the QoS data frame (11axstandard A-Control field), management frame, FILS discovery frame,unsolicited probe response frame, PS-Poll frame or Null frame, etc.),the AP MLD may transmit additional information to the non-AP MLD. Foranother example, a new frame may be defined as a frame for transmittingadditional information to a non-AP MLD.

For example, if the beacon period is rather long, essential informationrequired for link switching in the non-AP MLD may be insufficient or maynot be the latest information. Accordingly, the AP may transmit a frameincluding link capability information of the AP MLD to the non-AP MLD.After that, the non-AP STA may obtain the latest information on thecapability of each link of the AP MLD. The frame may be transmittedperiodically or aperiodically.

For example, when the frame is transmitted periodically, the AP maytransmit the frame to share the latest information of the AP at regulartime intervals. At this time, the time interval should be shorter thanthe beacon period transmitted by the AP. In addition, when a FILSdiscovery frame is used as the frame, the frame may be transmitted every20 us. As another example, a period agreed between the AP and the STAthrough capability negotiation may be used. For example, thetransmission period may be indicated through the “periodic” field andthe “interval” field/subfield value of the IOM capability element.

As another example, when the frame is transmitted aperiodically, the APmay transmit the frame whenever an update event occurs in information(capability, BSS parameter, operation element) of the AP. As a specificexample, whenever the link capability of the AP of the AP MLD ischanged, changed information may be transmitted to the connected STA. Inthis case, the STA may maintain up-to-date information on linkcapability.

According to the above-described example, since the non-AP STA does nottransmit a request message for acquiring a separate link capability,there is an effect of relatively less frame exchange overhead than thesolicited method. In addition, since the STA can receive the updatedinformation whenever the main information is updated, there is an effectthat the STA can use the received information usefully.

An example of specific AP MLD and non-AP MLD operations according to theunsolicited method can be described with reference to FIG. 22 .

FIG. 22 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

Referring to FIG. 22 , the AP MLD may transmit essential informationnecessary for link reselection in a separate frame (e.g., PS-Poll frameor Null frame) without a separate request message from the non-AP MLD tothe non-AP.

According to an embodiment, unlike FIG. 22 , the AP MLD transmitsinformation about link capability to the non-AP MLD without a separaterequest message of the non-AP MLD, and the fields of the DL frame (e.g.QoS data frame) transmitted by the AP MLD. It may also be transmitted tothe STA through. Operations of the AP MLD and non-AP MLD according tothe above embodiment may be described with reference to FIG. 23 .

FIG. 23 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

Referring to FIG. 23 , AP 2 may transmit information on another AP (orinformation about the other AP) to STA 2 based on a DL frame (i.e., DL1). In other words, the DL frame may include information about otherAPs. For example, information about other APs may be included in anA-Control field of the 802.11ax standard. According to the aboveembodiment, since an existing DL frame is used without a separatemessage, frame overhead can be reduced. If the critical information ofthe other AP is changed and real-time information is required, theupdate information may be transmitted through a separate message as inthe embodiment of FIG. 23 .

For example, Critical information of an AP may include the following Ato Q.

A. Inclusion of a Channel Switch Announcement element

B. Inclusion of an Extended Channel Switch Announcement element

C. Modification of the EDCA parameters element

D. Inclusion of a Quiet element

E. Modification of the DSSS Parameter Set

F. Modification of the CF Parameter Set element

G. Modification of the HT Operation element

H. Inclusion of a Wide Bandwidth Channel Switch element

I. Inclusion of a Channel Switch Wrapper element

J. Inclusion of an Operating Mode Notification element

K. Inclusion of a Quiet Channel element

L. Modification of the VHT Operation element

M. Modification of the HE Operation element

N. Insertion of a Broadcast TWT element

O. Inclusion of the BSS Color Change Announcement element

P. Modification of the MU EDCA Parameter Set element

Q. Modification of the Spatial Reuse Parameter Set element

Therefore, the non-AP MLD can acquire the latest Link capabilityinformation regardless of the Beacon frame period. Based on the receivedinformation, the non-AP MLD may select an appropriate Link during LinkSwitching. Based on the received information, the STA may request linkchange or reconnection to the AP MLD by reselecting an appropriate link.The request message may include AP information and Link information tobe reconnected. In addition, the AP MLD receiving this message maytransmit a response message of “Accept” when accepting the request, andmay transmit a response message of “Decline” when rejecting the request.

If the request is accepted, the AP can perform Link (re)setup throughframe exchange with the Link of the reselected AP after sending theresponse message. Conversely, in case of rejection, the STA can use theexisting linked Link as it is.

3) General Method

According to the general method, the non-AP MLD can request link changeor reconnection without requesting additional information based on theinformation it currently possesses. The information used at this timemay include AP MLD information and non-AP MLD information included inthe previously received Beacon or Management frame (e.g., STR capabilityinformation for each link, Link state (enable/disable) information,etc.).

Unlike the solicited method, the STA may directly transmit a link changeor reconnection request message to the AP MLD without requestingseparate information from the AP MLD. The request message may include APinformation to be reconnected with and Link information. Upon receivingthe request message, the AP MLD may transmit a response message of“Accept” when accepting the request, and a response message of “Decline”when rejecting the request.

If the request is accepted, the AP can perform frame exchange throughthe link with the reselected AP after sending the response message.Conversely, in case of rejection, the STA can use the existing linkedLink as it is.

Examples of specific AP MLD and non-AP MLD operations according to thegeneral method may be described with reference to FIG. 24 .

FIG. 24 illustrates operations of an AP MLD and a non-AP MLD for linkchange or reconnection.

Referring to FIG. 24 , STA 2 may want to directly change Link forreasons of QoS guarantee. If STA 2 has previously received informationfrom AP MLD (for example, information received through Beacon frame orManagement frame) or has already determined the Link it wants toreconnect to, STA 2 may request link change or reconnection without aseparate information request.

STA 2 may transmit STA information (e.g. STA ID, etc.) and Linkinformation to be changed (e.g. Link ID or AP BSS information, etc.) inthe Link switching request frame. Upon receiving this, the AP MLD maytransmit a Link switching response frame of “acknowledgment” to STA 3through the existing Link 2 when accepting the change. Thereafter, STA 2of the non-AP MLD may reconnect to AP 3 after performing a Link (re)setup process.

Signaling to Indicate Link Change and Reconnection Method

In order to indicate the methods proposed above, a mutual agreementprocess may be required through negotiation between the AP MLD and thenon-AP MLD. To this end, in the following specification, a signalingmethod for enabling methods to be proposed may be proposed.

First, a new element may be proposed to indicate the method proposedabove.

Hereinafter, an embodiment of signaling for indicating a link change andreconnection method is described, but the above embodiment can also beapplied to an embodiment of signaling for indicating an anchored linkchange and reconnection method.

The signaling process for indicating the link change and reconnectionmethod can be performed after multi-link setup or multi-link setup. Inaddition, new elements proposed below can be used in a signaling processfor indicating a link change and reconnection method. For example, theelements may be included in a (re)association frame of a conventionalstandard or a new frame.

IOM (Information Obtain Method) Capability Element

The IOM Capability Element may include information on whether a methodfor acquiring additional information for multi-link is enabled. Forexample, in a process in which an AP MLD and a non-AP MLD exchangemessages for operation agreement in a multi-link setup process (e.g.,capability negotiation process), an IOM capability value may exist in anelement of a message. The existence of an IOM capability value in anelement of the message may mean that the IOM capability is supported.

According to an embodiment, when the AP MLD supports the IOM capability,the AP may internally share information of the other AP and haveinformation of the other AP. An MLD in which other AP information is notshared cannot support the IOM capability.

According to an embodiment, when the value of the IOM capability elementis set to a first value (e.g., 1), the IOM capability element may meanactivating the IOM and operating with the indicated function.Conversely, when the value of the IOM capability element is set to asecond value (e.g., 0), the IOM capability element may mean inactivatingthe IOM.

According to one embodiment, the IOM capability element may includevarious fields/elements to indicate various operations. For example, theIOM capability element may include various fields/elements describedbelow. However, the field/element added to the IOM capability elementmay be set differently depending on the case where the AP MLD requeststhe link change and the case where the non-AP MLD requests the linkchange. In addition, at least some of the fields/elements added to theIOM capability element may be omitted. For example, amongfields/elements added to the IOM capability element, a field/elementincluding information that does not need to be indicated may be omitted.

Hereinafter, examples of various fields/elements defined/configured toobtain additional information on multi-links can be described. Variousfields/elements described below may be configured independently, or twoor more fields/elements may be combined and transmitted through variousframes. For example, various fields/elements described below may beincluded in other elements to perform defining operations. For anotherexample, various fields/elements described below may be added to otherelements as individual elements or independent fields and used.

Method Type (or Method) Field/Element

The method type field/element (hereinafter, Method field/element) mayinclude information about an operation method of the IOM. In otherwords, the Method field/element may indicate an operating method of theIOM. For example, when the Non-AP MLD activates the IOM method to obtaininformation from the AP, non-AP MLD can select and indicate the methodto be used among the methods proposed above (e.g., Solicited method,Unsolicited method, General method).

For example, a Solicited method may be indicated/used based on the firstvalue (e.g., 0) of the Method field/element. Based on the value of themethod field/element being the second value (e.g., 1), the unsolicitedmethod may be indicated/used. Based on the value of the methodfield/element being the third value (e.g., 2), the general method may beindicated/used. Based on the value of the Method field/element being thefourth value (e.g., 3), both the Solicited method and the Unsolicitedmethod may be indicated/used.

As another example, 1 bit may be used as a method field/element. In thiscase, based on the value of the method field/element being the firstvalue (eg: 0) (eg: 0), the Solicited method may be indicated/used. Basedon the value of the method field/element being the second value (e.g.,1), the unsolicited method may be indicated/used.

As another example, 2 bits may be used as a method field/element. Inthis case, single use or overlapping use for each method may beindicated.

Link Range Field/Element

When requesting information from the AP MLD, the non-AP MLD may indicatethe range of the requested link through a link range field/element. Thelink range field/element may include information about whether the STAwants to request information on all links within the AP MLD orinformation on some links within the AP MLD.

For example, when the value of the link range field/element is a firstvalue (e.g., 0), the link range field/element may mean that informationon all links within the AP MLD is requested. When the value of the linkrange field/element is a second value (e.g., 1), the link rangefield/element may mean that information on some links within the AP MLDis requested.

At this time, if the value of the link range field/element is the firstvalue (e.g., 0), since it is a request for all links in the AP MLD, aseparate link indication (e.g. “Link condition” field) information isnot required. Conversely, when the value of the link range field/elementis the second value (e.g., 1), link indicator information is requiredbecause information is requested for some links within the AP MLD. Forexample, this field can be included and used in the multi-link elementdefined in 802.11be. The currently defined multi-link element is shownin FIG. 25 .

FIG. 25 shows an example of a multi-link element added in a proberequest.

As shown in FIG. 25 , when a non-AP MLD transmits a request message torequest AP MLD information, a “Range” field can be added and used in theMulti-link Element. An example of this is shown in FIG. 26 .

FIG. 26 shows an example of using a Link Range field in a multi-linkelement.

As shown in FIG. 26 , the Link Range may be used together with the MLDMAC address field to indicate whether information of all links withinthe MLD is requested or information of some links is requested. At thistime, if the field value is 0, it means requesting information of alllinks, so additional link indicator information is not needed, so the“Per-STA Profile (x)” sub-element can be omitted.

In addition, this field may be used by being added to another elementwithout being included in the multi-link element defined by 802.11be. Anexample of this is shown in FIG. 27 .

FIG. 27 shows an example of a newly proposed field to indicate linkchange and reconnection.

As shown in FIG. 27 , several fields proposed in this specification maybe used together to indicate the range and conditions of informationrequested by the STA to the AP MLD in an integrated form as shown inFIG. 27 . Alternatively, the STA may independently include each proposedfield in the request message when requesting information from the APMLD, and may be omitted if unnecessary.

Info Range Field/Element

The Info range field may be used to indicate a range of information whena non-AP MLD requests information.

For example, when the value of the Info range field is a first value(e.g., 0), the Info range field may indicate that only partialinformation possessed by the AP is provided. When the value of the Inforange field is the second value (e.g., 1), the Info range field mayrepresent that all information (or all information) possessed by the APis provided.

According to one embodiment, an information range field may be definedto indicate a request for all or part of information (elements)possessed by the AP, but the STA may request more detailed informationthrough an additional subfield. For example, a subfield for indicating arange of information to be provided (e.g., all information or partialinformation) may be included in the information range field. Forexample, a subfield for indicating the range of information to beprovided may be defined/set as an all/partial subfield.

According to an embodiment, a subfield for indicating whether to receiveall information or whether to receive only changed information among allthe information may be newly proposed. In other words, the newlyproposed subfield may indicate whether to receive all information oronly changed information among all the information.

For example, a subfield indicating whether to receive all information oronly changed information among all the information may be defined/set asan only updated subfield.

If the STA wants to receive only changed information, the only updatedsubfield value may be set to 1. In other words, if the STA wants toreceive only changed information, the STA may set the only updatedsubfield value to 1. For example, when the only updated subfield valueis set to 1, according to the solicited method, when the STA requestsinformation, the AP (or AP MLD) can transmit only changed information(i.e., updated information) among the requested information. For anotherexample, when the only updated subfield value is set to 1, according tothe unsolicited method, the AP may notify only information changedwithin the information range set by the STA.

According to the above example, in order to receive only changedinformation, an only updated subfield in an information range field hasbeen proposed, but is not limited thereto. In order to receive onlychanged information, a separate field or element may bedefined/configured.

According to the above-described embodiment, the range of informationthat can be requested by the STA may be set to updated information orall information. In this case, an STA that does not want a lot of frameoverhead may request to receive only changed information. Therefore,there is an effect of reducing overhead.

Link Condition Field/Element

The Link condition field can be used to indicate the specific link beingrequested. In other words, the link condition field may includeinformation about a specific link requested. The link condition fieldmay be used when the STA wants to receive only specific link informationfrom the AP.

The link condition field may be displayed as a link identifier (e.g.Link ID, BSS ID). In other words, the link condition field may includeinformation about a link identifier (e.g. Link ID, BSS ID). In otherwords, a link identifier may be used to specify a link for obtaininginformation.

For example, if an STA connected to Link 1 wants to request onlyinformation about Link 2 and Link 3 from the AP, the STA may requestinformation on Link 2 and Link 3 from the AP by indicating link 2 andlink 3 in the link condition field. For example, when the value of theaforementioned info range field is 1, all information corresponding tolink 2 and link 3 can be transmitted. For another example, when thevalue of the aforementioned info range field is 0, partial informationdesignated by the STA may be transmitted on link 2 and link 3. Accordingto an embodiment, partial information designated by the STA may bedetermined through the following Info condition field.

According to an embodiment, when there is no value of the link conditionfield or is 0, the AP may determine that there is no link condition.Accordingly, the AP may provide/transmit information about all links tothe STA.

Info Condition Field/Element

The Info condition field can be used to indicate the specific type ofinformation being requested. In other words, the Info condition fieldmay be used when the STA wants to receive only specific information fromthe AP.

For example, the information condition field can be used only when theinfo range field is set to 0. For another example, the informationcondition field may be used by the STA to indicate specific informationeven when there is no info range field.

For example, within the information condition field, information thatcan be designated by the STA (e.g. BSS Load, STR Capability, etc.) maybe displayed as a Bitmap. For example, the type of information providedby the AP and the instruction method or order within the bit may be setin various ways.

According to an embodiment, the information condition field may be usedtogether with the above-described link condition field. According to anembodiment, the information condition field may transmit requestinformation of various conditions to the STA (or AP) based on acombination of various fields/elements.

In this regard, the element of the existing standard may be reused torequest that the STA indicate specific information. For example, RequestIE or Extended Request IE can be used. Element information for this isas shown in FIGS. 28 and 29 .

FIG. 28 shows an example of the Request IE format.

FIG. 29 shows an example of the Extended Request IE format.

The elements of FIGS. 28 and 29 may be used to request specificinformation in a probe request frame or an information request frame.When the STA indicates a list of information desired to be responded toas requested element IDs, the AP transmits the corresponding informationby including it in a probe response frame or information response frame.Therefore, in this specification, this element can be reused as anindicator for requesting specific information, and can also be used torequest desired information of a desired link together with a linkidentifier (e.g. Link identifier). For example, if the element ID forBSS load information is indicated in the request element mentioned inFIGS. 28 and 29 and information on AP 2 is indicated as a linkidentifier, only BSS load information of AP 2 can be requested. Thiselement ID information may be used to indicate specific information of aspecific AP in various combinations together with Link ID information.If, in the present disclosure, a new frame for information request isdefined instead of an existing frame, the Request element and ExtendedRequest element of FIGS. 28 and 29 can be reused.

In addition, the existing standard provides a PV1 Probe Response Optionelement to request specific information, and this element can be reusedas a method of indicating specific information. This is a method used bythe STA to request optional information with the desired information asa probe request. For frequently used information, each information isindicated with the probe response option bitmap as shown below. However,in the case of 11be, since multi-link information must be provided inconsideration of MLD, the STA can request specific information of aspecific link in various combinations using a link identifier along witha bitmap indicator as shown below. However, in this case, since theremay be optional information (e.g. STR capability) newly defined alongwith multi-link in 802.11be, if this PV1 Probe response option elementis reused, information newly defined in 11be or additionally required tobe acquired A bitmap for these must be newly defined or additionallydefined.

FIG. 30 shows an example of a PV1 Probe Response Option element format.

Transmission Periodic Field/Element

If the STA wants to receive information in an unsolicited manner, it mayindicate whether to periodically or aperiodically receive a messageincluding the information through a transmission periodic field.

For example, when the STA wants to receive the informationnon-periodically, the AP may notify the updated information wheneverinformation of other APs is updated.

For another example, when the STA instructs to periodically receive theinformation, the STA may receive a message including the information ata set periodic interval.

According to an embodiment, a transmission periodic field may be set to1 bit. When the value of the transmission periodic field is set to 1,the STA may receive/obtain information through a periodic method ofperiodically receiving messages. When the value of the transmissionperiodic field is set to 0, the STA may receive/obtain informationthrough a method of receiving messages aperiodically.

Transmission Interval (Interval) Field/Element

According to an embodiment, when the STA wants to periodically receiveinformation from other APs, the STA may directly set the period. The STAmay transmit information about a period for receiving other APinformation based on the transmission interval field. However, theperiod must be set shorter than the beacon transmission period. Forexample, when the FILS Discovery frame is used, the period must be setto 20 us.

As described above, it may be defined as a separate field within anelement indicating a transmission period, or may be defined as asubfield within a transmission periodic field.

According to an embodiment, a field/element defined/configured to obtainadditional information about multi-link is not limited to theabove-described field/element, and various fields/elements may befurther set.

Therefore, the MLD (AP MLD or non-AP MLD) can indicate the IOMcapability through negotiation between the AP MLD and the non-AP MLDusing at least one of the elements/fields described above in themulti-link setup process. In addition, the MLD can update the contentsof the agreement between the MLDs through a separate message exchangeafter the multi-link setup is completed.

According to an embodiment, when an IOM capability is activated, an APMLD and a non-AP MLD may operate based on an embodiment for link changeand reconnection.

Hereinafter, examples of operations of the AP MLD and the non-AP MLDwhen the IOM capability is activated may be described. For example, thenon-AP MLD may request additional information for multi-link bytransmitting the above-described fields/elements to the AP MLD. Thenon-AP MLD may transmit an IOM Capability element including theaforementioned fields/elements to the AP MLD. The inclusion of theabove-mentioned fields/elements in the IOM Capability element isexemplary, and may be transmitted as an independent field/element.

For example, in the multi-link setup process, the non-AP MLD maytransmit an IOM Capability element including “Method field=0” and “Inforange field=1” to the AP MLD and agree with the AP MLD. In this case,after multi-link setup, the non-AP MLD operates in a solicited method,and when requesting information, information for multi-link includingall information included in beacon (for example, information about otherAPs) may be requested. there is. Therefore, the AP MLD only receives arequest message from the STA. Link information can be provided/sent as aresponse message. Upon receiving the request message, the AP MLD maytransmit a response message including information on all links withinthe AP MLD to the STA. Information on all links in the AP MLD mayinclude all information included in beacons.

For another example, the non-AP MLD may transmit an IOM Capabilityelement including “Method field=1”, “Info range field=0”, “Linkrange=Link id 2”, “Info condition field=(value of BSS load displayedthrough bitmap), and may agree on this with the AP MLD. In this case,after multi-link setup, the non-AP MLD may operate in an unsolicitedmethod. Accordingly, the AP may transmit the BSS load information ofLink 2 to the STA through a separate message without a separate requestmessage.

For another example, the non-AP MLD may transmit an IOM Capabilityelement including “Method field=0”, “Info range field=0”, “only updatedfield or subfield=1”, “Info condition field=(BSS Load displayed throughbitmap value)” and may agree on this with the AP MLD. In this case,after multi-link setup, the non-AP MLD can operate in the Solicitedmethod. Accordingly, when the STA requests information, the AP MLD (orAP) may include only updated (changed) information among BSS loadinformation of all APs of the connected AP MLD in a response message andtransmit it to the STA.

In this specification, several options for a new element are proposed inorder for the STA to request partial information (i.e., targetinformation) of other APs of the connected AP MLD.

FIG. 31 shows an example of an MLD Request element.

Referring to FIG. 31 , “The number of Link ID” is a field for indicatingthe number of requested APs (i.e., links) when the STA requestsinformation on a specific AP.

“Link ID” is a field including indicator information of APs requested bythe STA.

For example, when the STA transmits the probe request frame includingthe above MLD request element, the AP receiving the request messageresponds with a probe response including all information of the APsindicated in the corresponding element. If the STA wants to requestpartial information, not all information of the indicated APs, transmitsthe Probe request frame along with the MLD request element and theRequest element or Extended request element defined in the existingstandard. Upon receiving this, the AP responds with a Probe responseincluding only the information indicated by the Request element orExtended request element.

Additionally, a new element in FIG. 32 is also proposed.

FIG. 32 shows another example of an MLD Request element.

Referring to FIG. 32 , “The number of Link ID” is a field for indicatingthe number of requested APs (i.e., links) when the STA requestsinformation on a specific AP.

“Link ID” is a field including indicator information of APs requested bythe STA.

“Requested Element IDs/Requested Element ID extensions” is a fieldincluding Element ID information of requested information when the STArequests specific information (i.e., element). This field includes onlyelement ID information when the Element ID corresponds to 0-254, andwhen the value is 255 or more, it is recognized as an Extended ElementID and Requested Element ID extensions information must be includedtogether. At this time, information corresponding to “Requested ElementIDs/Requested Element ID extensions” may be defined in the form of afield, but may be defined as a new element as shown in FIG. 33 andincluded in the form of a sub-element in the MLD Request element. A newelement for this can be defined as shown in FIG. 33 . This element hasthe advantage of reducing overhead as it can be indicated as one elementwithout distinguishing between existing request elements or extendedrequest elements.

FIG. 33 shows an example of defining a new element based on an MLDRequest element.

For example, when the STA transmits the probe request frame includingthe above MLD request element, the AP receiving the request messageresponds with a probe response including information on APs indicated inthe corresponding element.

Referring to FIG. 33 , the AP recognizes the information requested bythe STA as all or partial information depending on whether the“Requested Element IDs/Requested Element ID extensions” field is omittedin the corresponding element. Element ID value information defined inthe standard is defined in the 802.11 standard. In addition, thedefinitions of “Requested Element IDs” and “Element ID extensions”mentioned in this specification are the same as those of the existingstandards.

For example, when an STA requests information on an AP or other APs froman AP, the probe request frame includes the above MLD request elementand transmits it. Upon receiving this, the AP responds with a proberesponse frame by including only the information requested through the“Requested Element IDs/Requested Element ID extensions” field among theinformation of the APs requested through the “Link ID” field.

At this time, if the STA transmits by omitting the “Requested ElementIDs/Requested Element ID extensions” field, upon receiving this, the APresponds with a probe response frame including all information of therequested APs through the “Link ID” field.

The format proposed above can request only the same information for alllinks.

However, the STA may request different information for each linkdepending on the case. This specification proposes several options forthis.

First, as shown in FIG. 34 , a format for requesting differentinformation for each link is additionally proposed.

FIG. 34 shows another example of an MLD Request element.

As shown in FIG. 34 , the STA is a method of including and indicatingexisting Request element or/and Extended Request element information foreach link within the MLE Request element in order to request differentinformation for each link. At this time, a new field or element “Thenumber of Elements” is defined to inform the length of the requestedelement. This information means the number of elements requested forLink ID (x).

Upon receiving this, the AP checks the information requested differentlyfor each link based on the MLD Request element and responds by includingit in the Response frame.

In this case, the embodiment is shown in FIG. 35 when a field proposedby the present disclosure is used instead of the existing Requestelement or/and Extended Request element. Each field or element can beomitted as needed.

FIG. 35 shows another example of an MLD Request element.

Second, when the STA requests information, a format for distinguishingcommon information, which is equally requested for all links, and linkspecific information, which is requested differently for each link, isproposed as shown in FIG. 36 .

FIG. 36 shows another example of an MLD Request element.

As shown in FIG. 36 , when the Request element or/and Extended Requestelement is included in front of the number of Link ID field, it meanselements of common information commonly requested for links indicatedlater, Information listed after The number of Elements together withLink ID (x) behind the number of Link ID field means element informationrequested for each link. Each field or element can be omitted as needed.

In this case, an embodiment is shown in FIG. 37 when a field proposed bythe present disclosure is used instead of the existing Request elementor/and Extended Request element. Each field or element can be omitted asneeded.

FIG. 37 shows another example of an MLD Request element.

As shown in FIG. 37 , when the Request element or/and Extended Requestelement is included in front of the number of Link ID field, it meanselements of common information commonly requested for links indicatedlater, information listed after The number of Elements together withLink ID (x) behind the number of Link ID field means element informationrequested for each link. Each field or element can be omitted as needed.

Fourth, Common information, which is equally requested for all linkswhen the STA requests information, is used to indicate as a separateRequest element or Extended Request element together with the MLDRequest element as shown in FIG. 38 .

FIG. 38 shows an example of a field requesting common information.

When the STA requests information on multiple links of the AP MLDthrough a request frame, a method of indicating commonly requestedinformation through an existing Request or/and Extended Request Elementis proposed. In the case of information requested differently for eachlink, a method of indicating through the MLD Request element isproposed. The AP receiving this request message recognizes theinformation included in the Request or/and Extended Request Element asinformation commonly requested for the link indicated in the MLD Requestelement, and transmits the corresponding element information for alllinks indicated by the MLD request element in the response message. Inaddition, when the STA requests different information for each link, theAP includes it in the response message and transmits it based on theinformation indicated for each link in the MLD Request element.

This specification also proposes a method in which an STA requestspartial information of other APs of a connection AP MLD using amulti-link (ML) IE defined in the 802.11be standard.

FIG. 39 shows an example of the ML IE format defined in 802.11be.

In 802.11be, an ML Multi-Link Information Element (IE) is defined asshown in FIG. 39 to define information for each link. Elements or fieldscan be added later depending on the proposed function. In the Per-STAProfile (x) sub-element, various information about the link can beincluded. The corresponding sub-element includes the corresponding linkID and the contents of the information range included in thecorresponding sub-element through the Per-STA control field, and thenlists information (Element) corresponding to the information requestedby the STA. At this time, if there is non-inheritance information,information may be included using a non-inheritance element. TheComplete Profile in the Per-STA Control sub-element is a field thatdistinguishes whether the included information is complete informationor partial information of the link.

Therefore, by including this ML IE in the request frame (e.g. Proberequest frame), the STA can utilize it for requesting partialinformation from other APs, and various options are proposed for this.

In this specification, the following limiting factors are defined to useML IE for MLD probing. If the STA uses the ML IE in probe request famefor MLD probing, element information (e.g. Element x, . . . , Element n)provided by the Per-STA Profile (x) can be omitted and transmitted toreduce overhead. (However, when ML IE is used in the associationrequest/response frame used for association, element information must beincluded.). If the information requested by the STA is completeinformation of the link, the complete information bit is indicatedthrough the Per-STA Control field, and the subsequent elementinformation list is omitted and transmitted. If not, the Partialinformation bit is indicated through the Per-STA Control field, andinformation about the requested element ID is added to the back.However, various options related to the case where the STA requestspartial information for a specific element rather than completeinformation are defined in detail below.

As described above, in the ML IE defined by 802.11be, the includedinformation may be changed depending on whether the correspondingelement is included in the Association frame or the Probe frame orwhether the corresponding frame is a Request or Response. For example,if the STA uses the ML IE when making a probe request, elementscontaining various information in the Per-STA Profile (X) may beomitted, but if not, element information must be included. Therefore,this specification proposes a control field for indicating this.

The multi-link element and multi-link control field format defined inthe current 802.11be standard are shown in FIG. 40 .

FIG. 40 shows an example of a multi-link element format and a multi-linkcontrol field format.

At this time, a field for indicating the type of frame including thecurrent multi-link element is added to the multi-link control fieldelement. The proposed field is defined as “Elements per-STA Present”.The field name can be redefined as needed. This field indicates thepresence or absence of element list information for each STA requestedby the current ML IE. If the value is 1, it means that elementinformation behind the Per-STA Control field in the Per-STA Profile (x)field is included, and if it is 0, it means behind the Per-STA Controlfield in the Per-STA Profile (x) field. This means that elementinformation is omitted. An embodiment for this is shown in FIG. 41 .

FIG. 41 shows an example of a multi-link control field format.

In addition, as described above, in the ML IE defined by 802.11be, theincluded information may change depending on whether the correspondingelement is included in the Association frame or the Probe frame orwhether the corresponding frame is a Request or Response. Therefore, afield that can indicate this is proposed. The corresponding field isincluded in the ML IE of the request/response frame and indicates theframe type currently transmitted by the STA. Accordingly, the content orarrangement order of additional elements (elements composed of 0 orvariables) may change.

“frame type”: An indicator indicating the frame type currentlytransmitted by the STA. Depending on the value of the correspondingfield, the type of frame that currently includes the ML IE is indicated.For example, it can be indicated by classifying into 0: associationrequest, 1: association response, 3: probe request, 4: probe response,and the like. This can be expressed as an integer value or as a bitmap.In addition, if MLD probing configured in 802.11be is distinguished, 5:MLD probe request frame, 6: MLD probe response frame, etc. may beadditionally added. In this way, it is an indicator to indicate that theelement composition of ML IE is changed according to the frame type.Each frame type may be listed in the form of a subfield in the “frametype” field, and in the case of 1, the indicated frame type may beconfigured.

At this time, it may be classified into several subfields within “frametype” according to various functions of the transmitted frame.Therefore, in this specification, “request type”, which is a subfieldthat is classified according to the purpose of the frame in “frametype”, is defined. The corresponding “request type” subfield may beclassified in more detail in the message type classified as “frametype”, which can be classified according to the purpose of the currentlytransmitted frame. For example, if the “frame type” transmits the MLDprobe request frame to request all or part information on a specific AP,the “frame type” field is set to the MLD probe request frame (field=5),but the Whether the information is complete or partial, and whenrequesting partial information, what specific information (e.g. criticalupdate related information, link subset information that is not set upfor link re-setup, etc.) is requested as a “request type”. If the “frametype” is set as a (re)association request frame for link switching to aspecific AP, the “frame type” field is set as a (re)association requestframe (for reference, the MLD Probe request frame is currently used in802.11be). Since all frames except for the same basic type areclassified, the (re)association request frame will be classified asbasic type. However, the frame type classification may be changed in thefuture), the purpose of requesting the frame (e.g. TID-link mapping,link switching between MLDs, link switching within the same MLD), thiscan be indicated in the “request type” subfield. Upon receiving this,the non-AP STA or AP can determine the purpose of the frame transmittedby the STA in more detail through the subfield value transmitted alongwith the type of the currently received frame, and transmit appropriateinformation by including it in the response frame.

Various format options and operations for the ML IE regarding the casewhere the STA requests partial information for a specific element ratherthan complete information are proposed as follows.

First, it is a method of transmitting including a Request element or/andExtended Request element for indicating information that the STA wantsto request from the corresponding AP in the Per-STA Profile (x) in theexisting ML IE.

The AP receiving the request message indicating the correspondinginformation can know the partial information of the link that the STAwants to request through the ML IE information, and transmits theinformation by including it in the response frame (e.g. Probe responseframe). The STA indicates in the Request frame the Link ID it wants torequest through the Per-Control field in the Per STA Profile (x) in theML IE and whether the currently requested information is all (Complete)or partial (Partial), additionally, it is a method of displayingspecific information to be requested through Request element or/andExtended Request element. Using the format shown in FIG. 42 , the STAmay request specific desired information for each link. If the Requestelement or/and Extended Request element is omitted, it means that allinformation (i.e., complete information) of the corresponding AP isrequested. However, as suggested above, element information listed afterthe Per-STA Control field may be omitted if necessary.

FIG. 42 shows an example of the ML IE format.

Second, it is a method of transmitting including Requested ElementIDs/Requested Element ID extensions field for indicating informationthat the STA wants to request from the corresponding AP in the Per-STAProfile (x) in the existing ML IE. The corresponding field is defined inFIG. 43 as a field proposed in this specification.

FIG. 43 shows another example of the ML IE format.

Upon receiving the information, the AP can know the partial informationof the Link that the STA wants to request through the ML IE information,and transmits the information by including it in a response frame (e.g.Probe response frame). The STA indicates in the Request frame the LinkID it wants to request through the Per-STA Control field in the Per STAProfile (x) in the ML IE and whether the currently requested informationis Complete or Partial, additionally, it is a method of displayingspecific information to be requested through the Requested ElementIDs/Requested Element ID extensions field. Omitting the RequestedElement IDs/Requested Element ID extensions field means requesting allinformation (i.e., all elements information) of the corresponding AP. Anexample of the corresponding format is as follows. However, as suggestedabove, element information listed after the Per-STA Control field may beomitted if necessary.

The format of FIG. 43 has the advantage of reducing default fieldoverhead (e.g. element ID, length), etc. by transmitting elementindication information defined in the 802.11 standard as one piece ofinformation without dividing it into Request element or/and ExtendedRequest element.

Thirdly, by transmitting the Request element or/and Extended Requestelement to indicate the information that the STA wants to request fromeach AP, Common info and Link specific info that the STA wants torequest in common for all APs are distinguished. This is the format yourequest. The format is defined in FIG. 44 .

FIG. 44 shows another example of the ML IE format.

When the STA requests information of each AP through a request frame(e.g. Probe request frame), the same request may be made for partialinformation, and other information may be requested for each AP. Aformat for indicating this is defined and an embodiment is proposed. Asshown in FIG. 44 , the indicator for indicating the same informationthat the STA requests for the APs requesting information through therequest frame is used as a Request or/and Extended Request Elementtogether with the ML IE in the request frame, an indicator forindicating other information requested by each AP uses Request or/andExtended Element in Per-STA Profile (x). However, as suggested above,element information listed after the Per-STA Control field may beomitted if necessary.

For example, if the STA displays information corresponding to the TIMelement (e.g. Element 5=11) as a Request Element in the probe requestframe, indicates Per-STA Control of Per-STA Profile (x) in ML IE as LinkID=1, Complete Profile=0 (conversely, if the value is 1, it means allelements information request), displays information (e.g. Element ID=11)corresponding to the BSS load element in the Request Element, indicatesPer-STA Control of Per-STA Profile (y) as Link ID=2, Complete Profile=0,and indicates and transmits information corresponding to anon-inheritance element (e.g. Element ID=255, Element ID extension=56)in the Extended Request Element, the AP responds with a Probe Responseframe including the following information.

-   -   TIM element information for Link 1 and Link 2    -   BSS load element information for Link 1    -   Non-inheritance element information for Link 2

The STA can request different information for each link by dividing therequested information into Common or Link specific according to theelement hierarchy within the Frame.

In this way, in 802.11be, an inheritance model can be applied to the MLProbe request frame. As described above, when the STA transmitsincluding the (Extended) Request element in the ML probe request, thispartial information request is accepted by the peer AP as a commoninformation request for all APs as the inheritance model is applied notonly to the peer AP but also to the APs requested through the ML IE(i.e. Probe request variant Multi-Link Element). Therefore, whenreceiving a probe request frame including an (Extended) Request elementoutside the ML IE as shown in FIG. 44 from the STA, the AP may respondby including information corresponding to each AP in the ML IE (i.e.basic variant Multi-Link Element) in the Per-STA Profile by interpretingit as a common information request for the peer AP and requested APs(i.e. APs indicated for other AP information request in ML IE), and byconfirming the requested information indicated by the (Extended) Requestelement in the ML Probe response.

Fourth, by transmitting the Request element or/and Extended Requestelement in the Multi-link Element to indicate the information the STAwants to request from each AP, Common info and This is a format thatrequests Link specific info by classifying it. The format is defined inFIG. 45 .

FIG. 45 shows another example of the ML IE format.

When the STA requests information of each AP through a request frame(e.g. Probe request frame), the same request may be made for partialinformation, and other information may be requested for each AP foranother part of the information. A format for indicating this is definedand an embodiment is proposed. If the Request or/and Extended Requestelement is included along with the Multi-link element in the Requestframe (e.g. Probe request), this means that the STA requests partialinformation about the Link (ie associated AP) to which it is connected.If the STA requests information on APs other than its own link among theAPs of the connected AP MLD, the indication information for this isincluded in the ML multi-link element (IE). Therefore, if the Requestor/and Extended Request element is included before the Per-STA Profile(x) element within the ML IE as above, through the correspondingelement, information commonly requested for other APs of the AP MLDrequested by the STA (APs that do not correspond to its own link amongAPs included in the AP MLD to which the STA is connected) can beindicated. Information commonly requested for other APs is indicatedthrough the Request or/and Extended Request element in ML I.E., andinformation requested differently for each other AP is displayed behindthe Per-STA Control field in Per-STA Profile (x). It can be indicated byadding Request or/and Extended Request element. At this time, if thePer-STA Profile (x) in the ML IE includes an indicator of an APcorresponding to its own link rather than other APs, the STA can alsoobtain information of the AP corresponding to its own link through theML IE. In this case, the Request or/and Extended Request elementincluded with the ML IE can be omitted in order to request partialinformation of the AP corresponding to its own link.

However, as suggested above, element information listed after thePer-STA Control field may be omitted if necessary.

Fifth, the STA may request some complete information or some partialinformation about the Peer AP (i.e., transmitting link) and Other APs(i.e., Other link) through the MLD probe request. Several cases andembodiments related to this are as follows.

1) When Requesting Complete Information for Peer APs and RequestingComplete Information for Other APs

The EHT non-AP STA can transmit a message requesting all informationabout peer APs and other APs with one Probe Request frame.

FIG. 46 shows an example of a Probe Request frame including an ML IEformat.

Referring to FIG. 46 , when requesting complete information about a peerAP, the (Extended) Request element is not included in the Core of proberequest frame (frame body of the probe request frame), and theMulti-Link Element (i.e., probe request variant By setting the ‘Completeprofile’ subfield in the ‘Per-STA Control’ field in the Per-STA Profileof the Multi-Link Element) to 1, it indicates a request for allinformation about other APs.

2) When Requesting Complete Information for Peer APs and RequestingComplete or Partial Information for Other APs

2) When Requesting Complete Information for Peer APs and RequestingComplete or Partial Information for Other APs

The EHT non-AP STA can transmit a message requesting all informationabout the peer AP in one Probe Request frame and requesting all orpartial information about other APs indicated through the ML IE.

FIG. 47 shows another example of a Probe Request frame including an MLIE format.

Referring to FIG. 47 , when requesting complete information about a peerAP, when requesting partial information about other APs withoutincluding the (Extended) Request element in the Core of probe requestframe, The STA includes the (Extended) Request element in the Per-STAProfile of the Multi-Link Element (i.e., the probe request variantMulti-Link Element) and sets the ‘Complete profile’ subfield in the‘Per-STA Control’ field to 0 to Indicates a partial information requestto the AP. At this time, if the STA wants to request completeinformation about another AP, the STA can set the ‘Complete profile’subfield in the ‘Per-STA Control’ field to 1 without the (Extended)Request element in the Per-STA profile. In this way, the entireinformation request or partial information request for each AP can bemade with one Probe Request frame for other APs.

3) When Partial Information is Requested for Peer APs and Complete orPartial Information is Requested for Other Aps

The EHT non-AP STA requests partial information from the peer AP in oneProbe Request frame and can request all or partial information fromother APs indicated through the Multi-Link Element.

FIG. 48 shows another example of a Probe Request frame including an MLIE format.

Referring to FIG. 48 , when requesting partial information about a peerAP, an (Extended) Request element is included in the Core of proberequest frame, and when requesting complete information about other APs,the STA sets the ‘Complete profile’ subfield in the ‘Per-STA Control’field to 1 without the (Extended) Request element in the Per-STA Profileof the Multi-Link Element (i.e., the probe request variant Multi-LinkElement), and the STA A request for complete information about otherAPs.

At this time, if the STA wants to request partial information foranother AP, include the (Extended) Request element in the Per-STAprofile and set the ‘Complete profile’ subfield in the ‘Per-STA Control’field to 0. At this time, if the inheritance model is applied to the MLDprobe request, if the requested partial information is the same for thepeer AP and the AP (x) (i.e., Link) indicated in the Per-STA Profile(x), the (Extended) Request element in Per-STA Profile (x) may beomitted. That is, the (Extended) Request element is included in thePer-STA profile (x) only when it corresponds to the non-inheritanceelement for the (Extended) Request element included in the Core of proberequest frame, otherwise it can be omitted.

An embodiment when the inheritance model is applied to the MLD proberequest is shown in FIG. 49 .

FIG. 49 shows another example of a Probe Request frame including an MLIE format.

Referring to FIG. 49 , when an EHT non-AP STA requests partialinformation from a peer AP through an MLD probe request, an (Extended)Request element is included in the core of probe request frame. At thistime, in the case of requesting partial information different from thepeer AP for some APs (i.e., Per-STA Profile (x)) among the APs indicatedby the Multi-Link Element, non-information in the Per-STA Profile (x) isrequested. Other information can be requested by including the(Extended) Request element corresponding to the inheritance element. Atthis time, the Complete profile value of the Per-STA Control field isset to 0.

Or, when requesting the same partial information as the peer AP for someAPs (i.e., Per-STA Profile (y)) among the APs indicated by theMulti-Link Element, the STA omits the (Extended) Request element in thePer-STA Profile (y). At this time, the Complete profile value of thePer-STA Control field is set to 0. In this way, when the inheritancemodel is applied to the MLD probe request, if the EHT non-AP STArequests Element (a) and Element (b) from the peer AP and requestsElement (a) and Element (c) from the AP (x) indicated by the Per-STAProfile (x), Since there is information (e.g. Element (a)) that isequally requested from peer AP and AP (x), but also includes otherinformation (e.g. Element (c)), in order for the AP to distinguish this,the Per-STA Profile (x) must include an (Extended) Request elementindicating a request for information on Element (a) and Element (c).(When applying the inheritance model, if there is an (Extended) Requestelement in the Per-STA Profile(x), the AP recognizes it as anon-inheritance element even if there is overlapping requested partialinformation with the peer AP, so the same partial information as thepeer AP In the (Extended) Request element included in the Per-STAProfile (x), unless requesting the AP (e.g. AP (x) indicated through thePer-STA Profile (x), regardless of the partial information requested forthe peer AP)) must indicate all Element information requested). However,if the EHT non-AP STA requests Element (a) and Element (b) from the peerAP, and the EHT non-AP STA requests the same Element (a) and Element (b)to the AP (x) indicated by the Per-STA Profile (x)), since theinformation requested from the peer AP and AP (x) is the same, the STAapplies the inheritance model and sets the ‘Complete profile’ subfieldto 0 in the Per-STA Profile (x). The (Extended) Request elementindicating a request for information on Element (a) and Element (b) maybe omitted.

In this case, when the Complete profile value of the Per-STA Controlfield is set to 1, the inheritance model is not applied to the requestedinformation of the peer AP, but the complete information request for AP(y). That is, in order to apply the inheritance model to the Multi-Linkelement for the partial information request for the peer AP, theComplete profile value of the Per-STA Control field must be set to 0.

The STA may request different information for each link by dividing therequested information into common or link specific according to thearrangement of elements in the frame.

To this end, additionally, a new field is proposed in the Multi-LinkControl field to indicate whether the information requested by thecorresponding ML IE distinguishes Common information. As describedabove, the STA may express common information for a corresponding linkaccording to the arrangement of Request element or/and Extended Requestelement. Depending on whether Common information is requested, Requestelement or/and Extended Request element may exist before per-STA Profile(x) in ML IE in the request frame. Therefore, a control field forrepresenting this is proposed as shown in FIG. 50 .

FIG. 50 shows an example of a Multi-link Control field format.

The field of FIG. 50 may be defined as a ‘Common info Present’ field,and the corresponding name may be defined as another name later. If thefield is indicated as 1, when the STA requests information about otherAPs from the AP MLD, the Request element or/and Extended Request elementmeaning the same information request is included before the Per-STAProfile (x) element and transmitted. The field of FIG. 50 may be definedas a ‘Common info Present’ field, and the corresponding name may bedefined as another name later. If the field is indicated as 1, when theSTA requests information about other APs from the AP MLD, the Requestelement or/and Extended Request element meaning the same informationrequest is included before the Per-STA Profile (x) element andtransmitted. do. Link specific information requested differently foreach AP is indicated through the Request element or/and Extended Requestelement included in the Per-STA Profile (x) element. If the field isindicated as 0, it means that there is no information that the STAequally requests for other APs, and it means that there is no separateRequest element or/and Extended Request element before the Per-STAProfile (x) element.

An example for this is as follows.

The STA may make a partial request only for critical update informationto the AP of the AP MLD. To this end, this specification proposes twooptions. In this case, the AP may correspond to all APs (reporting APsand reported APs) that the STA can acquire through Beacon. Reported APrefers to other APs that the STA can acquire through the RNR element ofBeacon, and other APs in the same AP MLD as reporting APs, as well asother APs corresponding to the TxBSSID group and other APs correspondingto the non-TxBSSID group etc. In other words, the STA may requestcritical update information for all other APs capable of acquiring CSN(Change Sequence Number) information through Beacon (For reference,802.11be agreed to include change sequence field information of otherAPs in the RNR element of the Beacon frame).

First, a method of newly defining a ‘Critical update request’ field forrequesting critical update information from other APs.

-   -   ‘Critical update request’ field: A field requesting only system        information defined as critical update of the AP. Used together        with the link indicator, it can be used when requesting system        information defined as critical update of a specific link.

When the STA requests information on other APs of the AP MLD, if thecorresponding field value is set to 1 and transmitted along with thelink indicator information in the Request frame (e.g. Probe requestframe), upon receiving this, the AP responds by including criticalupdate information on the indicated link in the Response frame. At thistime, the critical update information (a) Inclusion of an ExtendedChannel Switch Announcement, b) Modification of the EDCA parameters, c)Modification of the S1G Operation element) means various systeminformation defined as critical update in the system information updateprocedure of the existing 802.11 standard. However, in the case of802.11be, new information can be additionally defined in addition to thepreviously defined system information for critical update, and thecritical update information mentioned in this specification meansinformation including critical update information newly defined in802.11be. If the corresponding field value is set to 0 and transmitted,the AP responds with a response frame as in the previous operation. Theproposed field can be included in any element within the Request frame,and can also be included and used in the MLD Request element or ML IEmentioned above. An embodiment for this is shown in FIG. 51 .

FIG. 51 shows an example in which the Critical update request field isincluded in the ML IE format.

Referring to FIG. 51 , when the STA requests information on specificlinks through the ML IE in the probe request, information correspondingto the specific link may be requested through Per-STA Profile (x). Atthis time, if the newly defined ‘Critical update request’ field isincluded in the Per-STA Control in the Per-STA Profile (x) and set to 1for transmission, the AP responds to the link indicated by the Per-STAProfile (x). Responds with response frame including current systeminformation defined as critical update. At this time, when the non-APSTA of the non-AP MLD transmits the ‘Critical update request’ fieldvalue set to 1 to request critical update information through the MLDProbe request, Change Sequence Number (CSN) information (e.g. ChangeSequence element, Change Sequence field, etc.) for each non-AP STA ofthe non-AP MLD may be transmitted together or omitted depending on theimplementation of the STA. In this case, if the critical updateinformation of APs is requested using the MLD probe request (i.e.,‘Critical update request’ field=1), if the Change Sequence element isused when including the CSN information, a separate additional indicatoris not necessary (because the AP can check the presence by checking theelement ID of the Change Sequence element), but if the Change Sequencefield is used as CSN information, a (sub)field to indicate the presenceor absence of the Change Sequence field (e.g. ‘CSN Presence’ subfield)needs additional definition. Therefore, in this specification, anindicator for displaying the presence or absence of CSN information inthe Per-STA profile of the ML IE is additionally proposed as follows.

-   -   ‘CSN Presence’ (sub)field: A field indicating that a change        sequence field exists. When the value is set to 1, it indicates        that the change sequence field exists, and when the value is 0,        it indicates that the change sequence field does not exist.    -   This field can be used together with the ‘Critical update        request’ field when the STA requests critical update information        from other APs (For example, the ‘CSN Presence’ (sub)field can        be used together with the ‘Critical update request’ (sub)field        in the per-STA Control field of the Per-STA Profile element in        the ML IE).    -   This field can also be used when the AP advertises CSN        information of APs (including reporting AP and reported AP)        through Beacon/Probe response. In the case of using the change        sequence element to advertise the corresponding CSN information,        the corresponding field is not required, but in case of using        the change sequence field, the ‘CSN Presence’ (sub)field        indicating the existence of the field is required. In this case,        the corresponding (sub)field may be included in various ways        according to the location where the CSN information of each AP        is included. It may be included in the Beacon/Probe response        frame (e.g. when the reporting AP's CSN information is located        in the Beacon/Probe response frame), included in the common info        part in the ML IE (e.g. when CSN information of reported AP is        located in common info part in ML IE), or included in the        per-STA Profile (e.g. when the CSN information of the reported        AP is located in the link info part in the ML IE).

At this time, if the non-AP STA uses an MLD probe request to requestcritical update information for each STA (x), (y) . . . etc., (that is,AP (x), (y) etc.,), when a non-AP STA requests critical updateinformation for STA (x) by setting the value of the ‘Critical updaterequest’ field of the Per-STA control in the Per-STA Profile (x) of theMulti-Link element (e.g. Probe Request variant Multi-Link element) to 1,depending on whether or not the CSN information is included, thereceiving AP may respond to the MLD probe response as follows.

1) When a non-AP STA transmits an MLD Probe request including its CSNinformation (That is, the most recently received CSN information may beincluded in the form of a change sequence element or change sequencefield) along with ‘Critical update request’ field=1 in Per-STA profile(x)

A. The AP compares the CSN information of the non-AP STA (x) with thecurrent CSN information of the AP (x) connected to the non-AP STA (x) toobtain updated critical update information (i.e., as a critical updateevent in 802.11be). classified elements) can be included in the MLDProbe response.

B. However, even in this case, if the received AP MLD does not implementthe function of tracking update information per CSN of the AP, since itis not known what information has been updated for each CSN version, itmay respond by including all current critical update information (i.e.,elements classified as critical update events in 802.11be) of the AP (x)connected to the non-AP STA (x) in the MLD Probe response.

C. In this specification, in order to reduce the overhead of the MLDprobe response, when requesting critical update information, it isproposed to respond with all current critical update information of AP(x) instead of all information of AP (x). Depending on the APimplementation, even if an MLD Probe request with the ‘Critical updaterequest’ field set to 1 in Per-STA profile (x) is received from a non-APSTA, the AP (x)'s Complete profile (i.e., complete information) may beresponded.

2) The non-AP STA transmits the MLD Probe request by omitting its CSNinformation (i.e., the most recently received CSN information) alongwith the ‘Critical update request’ field=1 in the Per-STA profile (x)case

A. Since the AP cannot know the CSN information of the non-AP STA (x),all current critical update information of the AP (x) connected to thenon-AP STA (x) (i.e., classified as a critical update event in 802.11be)elements) can be included in the MLD Probe response.

B. In this specification, in order to reduce the overhead of the MLDprobe response, when requesting critical update information, it isproposed to respond with all current critical update information of AP(x) instead of all information of AP (x). Depending on the APimplementation, even when receiving an MLD Probe request with the‘Critical update request’ field set to 1 in Per-STA profile (x) from anon-AP STA, it may respond with the complete profile (i.e., completeinformation) of AP (x).

FIG. 52 shows an example of an MLD probe request using a change sequenceelement when requesting critical update information.

FIG. 53 shows another example of an MLD probe request using a changesequence element when requesting critical update information.

For example, when a non-AP STA requests critical update information fora specific STA (x), as shown in FIG. 53 , critical update request=1 maybe set and change sequence number information (e.g. change sequenceelement or change sequence field) may be transmitted together. At thistime, the non-STA may omit and transmit the change sequence numberinformation depending on the case. However, in this case, as definedabove, the information included in the MLD Probe response from the APmay be limited.

FIG. 54 shows an example in which the Critical update request field isincluded in the ML IE format.

Referring to FIG. 54 , when the Critical update request field is locatedin the ML IE as above, critical update information for all linksindicated through the Per-STA Profile (x) can be requested. If theCritical update request field is included in a position that includescommon information in the ML I.E., and the field value is indicated as 1and transmitted, upon receiving this, the AP responds with a responseframe including critical update information for links requested in thecorresponding request frame. Alternatively, the Critical update requestfield may be included in a subfield within the multi-link control fieldin the ML IE to indicate. The shape of the field defined in this way(field, subfield, subelement, etc.) or location within the ML IE can bedefined in various ways according to the standard definition.

Second, a method using a change sequence element for requesting criticalupdate information from other APs. In 802.11ah, if the change sequenceelement is included in the probe request frame and transmitted, the APtransmits only the changed critical update information for thecorresponding link in the probe response frame in the compressed proberesponse frame. 802.11be can also take advantage of this.

When the STA makes a request by including a change sequence elementalong with link indicators for other APs in the probe request frame, theAP receiving the request includes only the changed critical updateinformation for the indicated links in the probe response and transmitsit. The change sequence element can be included in any element orsub-element in the request frame, and can also be included and used inthe above-mentioned MLD Request element or ML IE. An embodiment for thisis shown in FIG. 55 .

FIG. 55 shows an example in which a Change sequence element is includedin the ML IE format.

For example, when transmitting including a Change Sequence element inthe ML IE as shown in FIG. 55 , for the links indicated through the MLI.E., the AP compares the change sequence field value it currently haswith the change sequence field value in the change sequence elementtransmitted by the STA, and if there is a change, the AP responds byincluding the changed critical update information in the probe response.At this time, the change sequence element transmitted by the STA mustinclude change sequence information for all links requesting informationfrom the ML IE. Therefore, when using the existing change sequenceelement, additionally requested link indicator information may berequired. Additionally, in the present specification, when transmittingincluding the Change Sequence element in the ML IE as above, the optionof transmitting including all information related to the critical updatecurrently possessed by the AP is also considered. If the AP compares thevalue of the Change sequence field transmitted by the STA with the fieldcurrently possessed by the AP and finds a difference, the AP transmitsall information related to the currently possessed critical update tothe STA. This method may increase overhead for information transmittedby APs, but can be implemented more simply because there is no need tostore change information for each critical update version for each AP.

Additionally, in this specification, a new element considering MLD isadditionally proposed.

‘MLD Change Sequence element’: Element that can contain change sequenceinformation of multiple links

Examples for this are shown in FIGS. 56 and 57 .

FIG. 56 shows an example of an MLD Change Sequence format.

FIG. 57 shows another example of an MLD Change Sequence format.

As shown in FIG. 56 , the MLD change sequence value repeatedly listschange sequence values for each link, or as shown in FIG. 57 , afterindicating the number of links as ‘The number of Link ID’, Link IDinformation and Change sequence information may be indicatedrespectively.

An embodiment of the MLD Change Sequence element is shown in FIG. 58 .

FIG. 58 shows an example of an MLD Change Sequence element.

As shown in FIG. 58 , when the MLD Change sequence element is includedin the ML IE in the probe request frame and transmitted, the AP maycompare the change sequence value received for each link with its ownchange sequence value, and may respond by including changed criticalupdate information for links corresponding to the updated changesequence value in a response frame. In this case, if the STA does notrequest other information for each link, the Per-STA Profile (x)sub-element may be omitted and transmitted.

At this time, when using the existing Change Sequence element, it can beused as shown in FIG. 59 .

FIG. 59 shows an example of a change sequence element in the existingstandard.

Critical update information updated for each link may be requested byusing the existing change sequence element in the ML IE as it is. Anembodiment for this is shown in FIG. 59 .

FIG. 60 shows another example in which a change sequence element isincluded in the ML IE format.

Referring to FIG. 60 , when the STA transmits including a changesequence element in the Per-STA Profile (x) in the ML IE in the Proberequest, it means a request for changed critical update information ofthe link indicated by the Per STA Profile (x). Therefore, after checkingthe change sequence element included in the request frame, the APcompares the received change sequence value with its own change sequencevalue, and when there is an update (i.e., when there is changedinformation that the STA needs to update), the AP may transmit aresponse frame including changed critical update information or aresponse frame including all critical update related information.

Third, a change sequence field is used together with the ‘Criticalupdate request’ field defined above to request critical updateinformation from other APs. Above, as an indicator for the STA torequest information from other APs, the ‘Critical update request’ fieldis defined as follows.

-   -   ‘Critical update request’ field: A field requesting only system        information defined as critical update of the AP. Used together        with the link indicator, it can be used when requesting system        information defined as critical update of a specific link.

However, when the STA requests the critical update information of aspecific link with the 1-bit indicator as above, if the AP receiving therequest does not know the version of the critical update informationcurrently possessed by the STA (That is, the change sequence field valueof the critical update information of the STA), the AP must transmit aresponse message including all critical update information for therequested link. In addition, a Change Sequence element may be includedtogether with critical update information in the corresponding responseframe and transmitted. This is a rather simple method, but since it maybe redundant transmission of information already possessed by the STA, aformat is additionally proposed to reduce overhead. An example for thisis as follows.

FIG. 61 shows an example of a probe request frame for requestingcritical update information.

Referring to FIG. 61 , the STA may transmit a request frame by includinga Critical update request field, which is an indicator for requestingcritical update information, in a Request frame and Change sequencefields (or Change Sequence element) indicating version information ofthe critical update currently possessed by the STA. At this time, thechange sequence fields mean an indicator indicating a change sequencevalue for each link. In 802.11be, the STA can periodically receive achange sequence value for the APs of the connected AP MLD through abeacon or probe response, and since it is defined that the STA storesthese values, the STA Change sequence value information for each link isknown. Therefore, the Change sequence fields field defined in thisspecification means information on versions (i.e., change sequencevalues) of critical update information for APs of the connected AP MLDpreviously obtained by the STA through a Beacon or Probe response.

At this time, when the value of the ‘Critical update request’ field is1, it means that the STA requests critical update information, andotherwise, the value is indicated as 0. If the value of the ‘Criticalupdate request’ field is 1, it means a request for critical updateinformation, so it is transmitted including the Change sequence fieldsfield (or Change Sequence element), but if the value is 0, this field isomitted and transmitted. In other words, when the value of the ‘Criticalupdate request’ field is 1, the STA attaches Change sequence fields (orChange Sequence elements), and the receiving AP compares the receivedinformation with the current information it has and only changesinformation (i.e., Only changed information to be updated by the STA)can be transmitted in a response message, and when the value of the‘Critical update request’ field is 0, the change sequence fields (orchange sequence element) are omitted to reduce overhead. Additionally,in the present specification, when transmitting including the ChangeSequence fields in the ML IE as above, the option of transmittingincluding all information related to the critical update currentlypossessed by the AP is also considered. If the AP compares the value ofthe Change sequence field transmitted by the STA with the fieldcurrently possessed by the AP and finds a difference, the AP transmitsall information related to the currently possessed critical update tothe STA. This method may increase overhead for information transmittedby APs, but can be implemented more simply because there is no need tostore change information for each critical update version for each AP.

As above, the presence or absence of the change sequence field (orchange sequence element) can be classified and defined according to thevalue of the ‘Critical update request’ field, but depending on options,the ‘Critical update request’ field value and the Change sequence field(or Change Sequence element) may be independently defined and used. Inthis case, a case may occur when the request message transmitted by theSTA does not include the Change sequence fields field (or ChangeSequence element) together with the ‘Critical update request’ fieldhaving a value of 1, in this case, it is considered that the receivingAP wants to receive all critical update information, not only theupdated critical update information, and responds by including allcritical update information in the response message. In thisspecification, as shown below, a method that the STA transmits thepreviously acquired change sequence value information along with the‘Critical update request’ field, and the AP compares it with its currentchange sequence value information and transmits only the changedinformation in the response frame is proposed. At this time, thecorresponding section provides a Change sequence fields field as anexample to deliver change sequence information of the link, but the STAmay request a Change sequence element instead of the Change sequencefields field. However, since the use of the change sequence element hasalready been mentioned in the above section, the embodiment in which thechange sequence element is used together with the ‘Critical updaterequest’ field is omitted.

For example, when the STA transmits the Probe Request frame includingthe ML IE for MLD probing, information for requesting critical updatemay be included in a Per-STA Profile (x) subelement for requestinginformation for each STA as shown in FIG. 61 . At this time, theCritical update request field in the Per-STA Control field and theChange sequence fields field containing the Critical update informationof the current STA may be located in the Per-STA Profile (x). At thistime, the Critical update request field may be located together withChange sequence fields in the Per-STA Profile (x), not in the Per-STAControl field. An embodiment for this is shown in FIG. 62 .

FIG. 62 shows another example of a probe request frame for requestingcritical update information.

Upon receiving the request frame as shown in FIG. 62 , the AP sees theML IE information in the request frame and transmits a response messageincluding critical update information of a specific link requested bythe STA. At this time, if the Critical update request field exists inthe Per-STA Profile (x) element in the ML IE and the value is 1, it isrecognized that the STA has requested Critical update information. Inaddition, by comparing the change sequence information of the STA withthe current change sequence information for the link (X) requested bythe STA through the change sequence fields information received togetherat this time, If there is something updated (that is, if there ischanged information that the STA needs to update), a compressed proberesponse frame containing only the updated information is transmitted,or if there are updated items, all information related to the criticalupdate can be responded with a probe response frame.

The information mentioned above is included in the Common info levelrather than the Link specific level in ML I.E., so that critical updateinformation can be requested for all links at once, not for specificlinks.

An embodiment for this is shown in FIG. 63 .

FIG. 63 shows another example of a probe request frame for requestingcritical update information.

As shown in FIG. 63 , the STA requests including the Critical updaterequest field (i.e., setting the value to 1) and Change sequence fieldsin the Link specific information location (e.g. Common informationlocation rather than Per-STA Profile (x)) in the ML IE frame can betransmitted. Upon receiving this, the AP recognizes the STA as a requestfor all of its own links, not a specific link, and compares the changesequence fields information transmitted by the STA with the currentchange sequence information for all of its own links. (that is, if thereis changed information that the STA needs to update), it transmits acompressed probe response frame containing only updated information forall links, or if there are updated items, all information related to thecritical update can be responded with a probe response frame.

FIG. 64 shows another example of a probe request frame for requestingcritical update information.

At this time, the STA may indicate a request for the changed criticalupdate information of the link by placing the critical update requestfield in the multi-link control field as shown in FIG. 64 .

Regarding the above method of requesting critical update changeinformation for a specific AP by the STA, in this specification, aresponse operation to which the AP responds is additionally proposed. Inthe current 802.11ax standard, when a 6 GHz AP receives a Probe Requestand transmits a Probe Response frame, if the AP does not indicate theactual SSID of the SSID element of its Beacon frame, the sending rule bysetting the broadcast address in the Address 1 field is already defined.Referring to this, in the 802.11be standard, when an MLD Probe Requestframe requesting complete information about an AP operating in the 2.4GHz band or 5 GHz band is received, when the AP responds to the MLDProbe Response frame, if the AP does not indicate the actual SSID of theSSID element of its Beacon frame, a method for setting the Address 1field to a broadcast address is being discussed.

In contrast, in the present specification, even when the STA requestsupdate-related information on a critical update for a specific APthrough the MLD Probe Request frame (for example, when the STA transmitsthe MLD Probe Request frame with Change Sequence field informationincluded), when the AP responds to the MLD Probe Response frame, if theAP does not indicate the actual SSID of the SSID element of its Beaconframe, a method for setting the Address 1 field to a broadcast addressis proposed. Critical update information is important change informationof an AP and is information that all STAs must know before datatransmission/reception. Therefore, in order to prevent a storm caused byMLD probing, the present specification proposes a method of respondingwith a broadcast message when a STA requests partial information on acritical update of a specific AP, unless otherwise indicated.

In addition, as described above, depending on the implementation of theAP MLD, the AP MLD may implement a method of storing which information(i.e., IEs) has been updated for each CSN (Change Sequence Number,whenever a critical update occurs) of each AP, depending on the memorysize, it may not be implemented. If the corresponding method issupported, the AP needs to remember which IE information has beenupdated whenever its CSN is changed. For example, if the AP generates acritical update event for Element X at CSN n=1 and updates for ElementsY and Z at CSN=n+1, then the AP determines what happens at CSN=n and CSNn+1. It should be possible to keep the information to see if it haschanged. If the AP can track which IE has changed for each CSN likethis, when the STA transmits the CSN information it is currently storingin the Request frame, it can be useful in terms of overhead because onlychanged information compared to the current CSN value of the AP, not allinformation, can be included in the response frame and transmitted.However, this tracking may not be easy, and since additional memory isrequired for the AP, the corresponding capability may or may not besupported depending on the implementation specifications of the AP.Therefore, the present disclosure proposes a capability for indicatingthe ability of the AP to track update information for each CSN asfollows.

-   -   ‘Critical update Tracking Support’ field: This field is        information indicating whether or not the current STA or AP        supports a function for storing which information (e.g. EI        (Element ID) information) has been updated for each CSN value.        If the value is 1, it means that the STA or AP supports the        ability to store which information has been updated for each CSN        value, and if it is 0, it means that the STA or AP does not        support the corresponding function. For example, this Field may        be included in an Extended Capabilities element or an EHT        Capabilities element.

The STA can use it to request critical update information for a specificAP (or STA) by checking whether the corresponding AP (or STA) supportsthis function in the association process. This function may be supportedat the MLD level or at the STA level for each STA.

According to an embodiment, the AP MLD and the non-AP MLD can activatethe IOM method proposed in the multi-link setup process or after themulti-link setup through the signaling method proposed in thisspecification. In addition, AP MLD and non-AP MLD can limit the rangeand type of requested information through various field values in theIOM Capability element.

According to an embodiment, the IOM operation may be performed afterprecise operation negotiation between MLDs through the above-describedIOM signaling method, but the IOM operation may be performed by the MLDimplementation without a separate signaling process. This may mean thatit operates by implementing an AP MLD or by implementing a non-AP MLDwithout negotiation between the AP MLD and the non-AP MLD.

Based on the above-described embodiments, AP MLD and non-AP MLD canoperate, but the following restrictions may occur when the MLD performsan IOM operation without separate signaling exchange.

1) Constraints on the Solicited method: If information sharing is notsupported between APs in the AP MLD, it cannot respond when the STArequests information on another link.

2) Constraints on the unsolicited method: The AP can provide a separatemessage by determining the STA that needs link additional information(e.g. beacon period, etc.). Therefore, the STA cannot predict in advancewhether it will receive this information.

When the MLD implements the IOM without a separate signaling method,there is an effect of simplifying the operation process, but there is aproblem that the above-mentioned limitations may occur.

According to an embodiment, a method for requesting multi-linkinformation may be set based on an agreement between an AP MLD and anon-AP MLD performed using the above-described IOM capability element.In contrast, in the case of the solicited method, the STA may want toacquire the information temporarily by instructing specific informationother than the agreed content. In this case, when the STA dynamicallysends a request message, the request may include the content indicated(e.g., IOM capability information).

For example, during or after multi-link setup, the AP MLD and the non-APMLD agree and the STA may receive information from the AP based on theagreed content, but the STA may want to temporarily request informationof a specific AP or specific parameter information of APs. In this case,when requesting information, the STA may transmit an “TOM capability”element in a request frame (e.g. probe request frame or (re)associationframe or new frame) including instructions for the information it wantsto request. Based on the request frame, the AP may transmit/provide aresponse message including information requested by the STA to the STA.According to an embodiment, when a field in an IOM capability element isomitted, the AP may provide information to the STA based on previouslyagreed content.

Accordingly, the MLD (AP MLD or non-AP MLD) may perform negotiationbetween the AP MLD and the non-AP MLD using the above-described elementduring a multi-link setup process or thereafter. Based on thenegotiation, the non-AP MLD may perform an agreement on information tobe provided (or information to be received) and receive it. In addition,the STA may temporarily receive only requested information bytransmitting a request message including instructions for informationdesired to be requested. However, if special instructions are omitted inthe request message, the non-AP MLD and AP MLD may operate based on thebasic agreed upon indications.

According to an embodiment, if the contents of the agreement are to bechanged after completion of the multi-link setup, the non-AP MLD and theAP MLD may update the contents of the agreement between the MLDs througha separate message exchange.

Hereinafter, the above-described embodiment will be described withreference to FIGS. 1 to 64 .

FIG. 65 is a flowchart illustrating a procedure in which a transmittingMLD provides requested information of an AP to a receiving MLD based ona probe response frame according to the present embodiment.

The example of FIG. 65 may be performed in a network environment inwhich a next generation WLAN system (IEEE 802.11be or EHT WLAN system)is supported. The next generation wireless LAN system is a WLAN systemthat is enhanced from an 802.11ax system and may, therefore, satisfybackward compatibility with the 802.11ax system.

In this embodiment, when a non-AP STA requests the same partialinformation as a peer AP for an AP other than a peer AP in MLDcommunication, a method and apparatus for transmitting a probe requestframe or receiving a probe response frame by omitting an (Extended)Request element in a profile field of another AP are proposed. Here, thetransmitting MLD may correspond to the AP MLD, and the receiving MLD maycorrespond to the non-AP MLD. If the non-AP STA is a first receivingSTA, a first transmitting STA connected to the first receiving STAthrough a first link may be referred to as a peer AP, and the second tofourth transmitting STAs connected through different links may bereferred to as different APs.

In step S6510, a transmitting multi-link device (MLD) receives a proberequest frame from a receiving MLD through a first link.

In step S6520, the transmitting MLD transmits a probe response frame tothe receiving MLD through the first link.

The transmitting MLD includes a first transmitting station (STA)operating on the first link and a second transmitting STA operating on asecond link. The receiving MLD includes a first receiving STA operatingon the first link and a second receiving STA operating on the secondlink.

When the first receiving STA requests partial information on the firstand second links, the probe request frame includes a first requestelement and a multi-link element.

Partial information on the first link is requested based on the firstrequest element. The first request element is an (Extended) RequestElement and may be included in a frame body of the probe request frameinstead of being included in the multi-link element. That is, when thefirst receiving STA requests partial information on the firsttransmitting STA (peer AP), the first request element may be included inthe probe request frame, and information may be specified for eachelement identifier (element ID) in the first request element. However,when the first receiving STA requests complete information on the firsttransmitting STA, the first request element may not be included in theprobe request frame. The first transmitting STA may confirm that thefirst receiving STA is requesting the complete information because thefirst request element is not included in the probe request frame.

The multi-link element includes a profile field of the second receivingSTA. That is, the multi-link element can be used when requestinginformation on an AP other than a peer AP.

The profile field of the second receiving STA includes a first completeinformation profile subfield.

When partial information on the first link and partial information onthe second link are the same, partial information on the second link isrequested based on the first request element, and a value of the firstcomplete information profile subfield is set to 0. That is, when thefirst receiving STA requests the same partial information as the firstlink for the second link, since partial information on the second linkcan be requested through the first request element ((Extended) RequestElement) included in the probe request frame, since the partialinformation on the second link can be requested through the firstrequest element ((Extended) Request Element) included in the proberequest frame, a profile field of the second receiving STA may betransmitted without including a separate (Extended) Request Element.This method may be referred to as a method in which an inheritance modelis applied to a (MLD) probe request frame. However, the value of thefirst complete information profile subfield may be set to 0 to notifythe second transmitting STA that partial information is being requestedfor the second link. This has an effect of reducing overall frameoverhead by preventing unnecessary duplication of information.

In addition, the transmitting MLD may further include a thirdtransmitting STA operating in a third link, and the receiving MLD mayfurther include a third receiving STA operating in the third link.

The multi-link element may further include a profile field of the thirdreceiving STA, and the profile field of the third receiving STA mayinclude a second complete information profile subfield.

When the first receiving STA requests partial information on the firstand third links and the partial information on the first link and thepartial information on the third link are not the same, the profilefield of the third receiving STA may include a second request element,partial information on the third link may be requested based on thesecond request element, and a value of the second complete informationprofile subfield may be set to 0. In this case, since the firstreceiving STA does not request the same partial information as the firstlink for the third link, a separate (Extended) Request Element (thesecond request element) must be included in the profile field of thethird receiving STA. However, since the first receiving STA requestspartial information for the third link, the value of the second completeinformation profile subfield may be set to 0. In this case, a valueindicated by the identifier included in the first request element may bedifferent from a value indicated by an identifier included in the secondrequest element. That is, information indicated by an Element ID of thefirst request element and information indicated by an Element ID of thesecond request element are inevitably different from each other.

In addition, the transmitting MLD may further include a fourthtransmitting STA operating in a fourth link, and the receiving MLD mayfurther include a fourth receiving STA operating in the fourth link.

The multi-link element may further include a profile field of the fourthreceiving STA, and the profile field of the fourth receiving STA mayinclude a third complete information profile subfield.

When the first receiving STA requests the partial information on thefirst link and complete information on the fourth link, the completeinformation on the fourth link may be requested based on the profilefield of the fourth receiving STA, and a value of the third completeinformation profile subfield may be set to 1. In this case, since thefirst receiving STA requests the complete information on the fourthlink, the profile field of the fourth receiving STA does not need toinclude a separate (Extended) Request Element, and only the value of thethird complete information profile subfield needs to be set to 1. Thefourth transmitting STA may confirm that the complete information hasbeen requested from itself based on the profile field of the fourthreceiving STA.

FIG. 66 is a flowchart illustrating a procedure for a receiving MLD torequest information of an AP from a transmitting MLD based on a proberequest frame according to the present embodiment.

The example of FIG. 66 may be performed in a network environment inwhich a next generation WLAN system (IEEE 802.11be or EHT WLAN system)is supported. The next generation wireless LAN system is a WLAN systemthat is enhanced from an 802.11ax system and may, therefore, satisfybackward compatibility with the 802.11ax system.

In this embodiment, when a non-AP STA requests the same partialinformation as a peer AP for an AP other than a peer AP in MLDcommunication, a method and apparatus for transmitting a probe requestframe or receiving a probe response frame by omitting an (Extended)Request element in a profile field of another AP are proposed. Here, thetransmitting MLD may correspond to the AP MLD, and the receiving MLD maycorrespond to the non-AP MLD. If the non-AP STA is a first receivingSTA, a first transmitting STA connected to the first receiving STAthrough a first link may be referred to as a peer AP, and the second tofourth transmitting STAs connected through different links may bereferred to as different APs.

In step S6610, a receiving multi-link device (MLD) transmits a proberequest frame to a transmitting MLD through a first link.

In step S6620, the receiving MLD receives a probe response frame fromthe transmitting MLD through the first link.

The transmitting MLD includes a first transmitting station (STA)operating on the first link and a second transmitting STA operating on asecond link. The receiving MLD includes a first receiving STA operatingon the first link and a second receiving STA operating on the secondlink.

When the first receiving STA requests partial information on the firstand second links, the probe request frame includes a first requestelement and a multi-link element.

Partial information on the first link is requested based on the firstrequest element. The first request element is an (Extended) RequestElement and may be included in a frame body of the probe request frameinstead of being included in the multi-link element. That is, when thefirst receiving STA requests partial information on the firsttransmitting STA (peer AP), the first request element may be included inthe probe request frame, and information may be specified for eachelement identifier (element ID) in the first request element. However,when the first receiving STA requests complete information on the firsttransmitting STA, the first request element may not be included in theprobe request frame. The first transmitting STA may confirm that thefirst receiving STA is requesting the complete information because thefirst request element is not included in the probe request frame.

The multi-link element includes a profile field of the second receivingSTA. That is, the multi-link element can be used when requestinginformation on an AP other than a peer AP.

The profile field of the second receiving STA includes a first completeinformation profile subfield.

When partial information on the first link and partial information onthe second link are the same, partial information on the second link isrequested based on the first request element, and a value of the firstcomplete information profile subfield is set to 0. That is, when thefirst receiving STA requests the same partial information as the firstlink for the second link, since partial information on the second linkcan be requested through the first request element ((Extended) RequestElement) included in the probe request frame, since the partialinformation on the second link can be requested through the firstrequest element ((Extended) Request Element) included in the proberequest frame, a profile field of the second receiving STA may betransmitted without including a separate (Extended) Request Element.This method may be referred to as a method in which an inheritance modelis applied to a (MLD) probe request frame. However, the value of thefirst complete information profile subfield may be set to 0 to notifythe second transmitting STA that partial information is being requestedfor the second link. This has an effect of reducing overall frameoverhead by preventing unnecessary duplication of information.

In addition, the transmitting MLD may further include a thirdtransmitting STA operating in a third link, and the receiving MLD mayfurther include a third receiving STA operating in the third link.

The multi-link element may further include a profile field of the thirdreceiving STA, and the profile field of the third receiving STA mayinclude a second complete information profile subfield.

When the first receiving STA requests partial information on the firstand third links and the partial information on the first link and thepartial information on the third link are not the same, the profilefield of the third receiving STA may include a second request element,partial information on the third link may be requested based on thesecond request element, and a value of the second complete informationprofile subfield may be set to 0. In this case, since the firstreceiving STA does not request the same partial information as the firstlink for the third link, a separate (Extended) Request Element (thesecond request element) must be included in the profile field of thethird receiving STA. However, since the first receiving STA requestspartial information for the third link, the value of the second completeinformation profile subfield may be set to 0. In this case, a valueindicated by the identifier included in the first request element may bedifferent from a value indicated by an identifier included in the secondrequest element. That is, information indicated by an Element ID of thefirst request element and information indicated by an Element ID of thesecond request element are inevitably different from each other.

In addition, the transmitting MLD may further include a fourthtransmitting STA operating in a fourth link, and the receiving MLD mayfurther include a fourth receiving STA operating in the fourth link.

The multi-link element may further include a profile field of the fourthreceiving STA, and the profile field of the fourth receiving STA mayinclude a third complete information profile subfield.

When the first receiving STA requests the partial information on thefirst link and complete information on the fourth link, the completeinformation on the fourth link may be requested based on the profilefield of the fourth receiving STA, and a value of the third completeinformation profile subfield may be set to 1. In this case, since thefirst receiving STA requests the complete information on the fourthlink, the profile field of the fourth receiving STA does not need toinclude a separate (Extended) Request Element, and only the value of thethird complete information profile subfield needs to be set to 1. Thefourth transmitting STA may confirm that the complete information hasbeen requested from itself based on the profile field of the fourthreceiving STA.

The technical features of the present disclosure may be applied tovarious devices and methods. For example, the technical features of thepresent disclosure may be performed/supported through the device(s) ofFIG. 1 and/or FIG. 11 . For example, the technical features of thepresent disclosure may be applied to only part of FIG. 1 and/or FIG. 11. For example, the technical features of the present disclosure may beimplemented based on the processing chip(s) 114 and 124 of FIG. 1 , orimplemented based on the processor(s) 111 and 121 and the memory(s) 112and 122, or implemented based on the processor 610 and the memory 620 ofFIG. 11 . For example, the device according to the present disclosuretransmits a probe request frame to a transmitting multi-link device(MLD) through a first link; and receives a probe response frame from thetransmitting MLD through the first link.

The technical features of the present disclosure may be implementedbased on a computer readable medium (CRM). For example, a CRM accordingto the present disclosure is at least one computer readable mediumincluding instructions designed to be executed by at least oneprocessor.

The CRM may store instructions that perform operations includingtransmitting a probe request frame to a transmitting multi-link device(MLD) through a first link; and receiving a probe response frame fromthe transmitting MLD through the first link. At least one processor mayexecute the instructions stored in the CRM according to the presentdisclosure. At least one processor related to the CRM of the presentdisclosure may be the processor 111, 121 of FIG. 1 , the processing chip114, 124 of FIG. 1 , or the processor 610 of FIG. 11 . Meanwhile, theCRM of the present disclosure may be the memory 112, 122 of FIG. 1 , thememory 620 of FIG. 11 , or a separate external memory/storagemedium/disk.

The foregoing technical features of the present specification areapplicable to various applications or business models. For example, theforegoing technical features may be applied for wireless communicationof a device supporting artificial intelligence (AI).

Artificial intelligence refers to a field of study on artificialintelligence or methodologies for creating artificial intelligence, andmachine learning refers to a field of study on methodologies fordefining and solving various issues in the area of artificialintelligence. Machine learning is also defined as an algorithm forimproving the performance of an operation through steady experiences ofthe operation.

An artificial neural network (ANN) is a model used in machine learningand may refer to an overall problem-solving model that includesartificial neurons (nodes) forming a network by combining synapses. Theartificial neural network may be defined by a pattern of connectionbetween neurons of different layers, a learning process of updating amodel parameter, and an activation function generating an output value.

The artificial neural network may include an input layer, an outputlayer, and optionally one or more hidden layers. Each layer includes oneor more neurons, and the artificial neural network may include synapsesthat connect neurons. In the artificial neural network, each neuron mayoutput a function value of an activation function of input signals inputthrough a synapse, weights, and deviations.

A model parameter refers to a parameter determined through learning andincludes a weight of synapse connection and a deviation of a neuron. Ahyper-parameter refers to a parameter to be set before learning in amachine learning algorithm and includes a learning rate, the number ofiterations, a mini-batch size, and an initialization function.

Learning an artificial neural network may be intended to determine amodel parameter for minimizing a loss function. The loss function may beused as an index for determining an optimal model parameter in a processof learning the artificial neural network.

Machine learning may be classified into supervised learning,unsupervised learning, and reinforcement learning.

Supervised learning refers to a method of training an artificial neuralnetwork with a label given for training data, wherein the label mayindicate a correct answer (or result value) that the artificial neuralnetwork needs to infer when the training data is input to the artificialneural network. Unsupervised learning may refer to a method of trainingan artificial neural network without a label given for training data.Reinforcement learning may refer to a training method for training anagent defined in an environment to choose an action or a sequence ofactions to maximize a cumulative reward in each state.

Machine learning implemented with a deep neural network (DNN) includinga plurality of hidden layers among artificial neural networks isreferred to as deep learning, and deep learning is part of machinelearning. Hereinafter, machine learning is construed as including deeplearning.

The foregoing technical features may be applied to wirelesscommunication of a robot.

Robots may refer to machinery that automatically process or operate agiven task with own ability thereof. In particular, a robot having afunction of recognizing an environment and autonomously making ajudgment to perform an operation may be referred to as an intelligentrobot.

Robots may be classified into industrial, medical, household, militaryrobots and the like according uses or fields. A robot may include anactuator or a driver including a motor to perform various physicaloperations, such as moving a robot joint. In addition, a movable robotmay include a wheel, a brake, a propeller, and the like in a driver torun on the ground or fly in the air through the driver.

The foregoing technical features may be applied to a device supportingextended reality.

Extended reality collectively refers to virtual reality (VR), augmentedreality (AR), and mixed reality (MR). VR technology is a computergraphic technology of providing a real-world object and background onlyin a CG image, AR technology is a computer graphic technology ofproviding a virtual CG image on a real object image, and MR technologyis a computer graphic technology of providing virtual objects mixed andcombined with the real world.

MR technology is similar to AR technology in that a real object and avirtual object are displayed together. However, a virtual object is usedas a supplement to a real object in AR technology, whereas a virtualobject and a real object are used as equal statuses in MR technology.

XR technology may be applied to a head-mount display (HMD), a head-updisplay (HUD), a mobile phone, a tablet PC, a laptop computer, a desktopcomputer, a TV, digital signage, and the like. A device to which XRtechnology is applied may be referred to as an XR device.

The claims recited in the present specification may be combined in avariety of ways. For example, the technical features of the methodclaims of the present specification may be combined to be implemented asa device, and the technical features of the device claims of the presentspecification may be combined to be implemented by a method. Inaddition, the technical characteristics of the method claim of thepresent specification and the technical characteristics of the deviceclaim may be combined to be implemented as a device, and the technicalcharacteristics of the method claim of the present specification and thetechnical characteristics of the device claim may be combined to beimplemented by a method.

What is claimed is:
 1. A method in a wireless local area network (WLAN)system, the method comprising: transmitting, by a first non-access point(AP) station (STA), a probe request frame to a first AP; and receiving,by the first non-AP STA, a probe response frame from the first AP,wherein the first AP operating on a first link and a second AP operatingon a second link are affiliated with an AP multi-link device (MLD),wherein the first non-AP STA operating on the first link and a secondnon-AP STA operating on the second link affiliated with a non-AP MLD,wherein based on the first non-AP STA requesting partial information onthe first and second APs, the probe request frame includes a firstrequest element and a multi-link element, wherein the partialinformation on the first AP is requested based on the first requestelement, wherein the multi-link element includes a profile field for thesecond AP, wherein the profile field for the second AP includes a firstComplete Profile Requested subfield, and wherein based on the partialinformation on the first AP and the partial information on the second APare the same, the partial information on the second AP is requestedbased on the first request element, and a value of the first CompleteProfile Requested subfield is set to
 0. 2. The method of claim 1,wherein a third AP operating on a third link is further affiliated withthe AP MLD, wherein a third non-AP STA operating on the third link isfurther affiliated with the non-AP MLD, wherein the multi-link elementfurther includes a profile field for the third AP, wherein the profilefield for the third AP includes a second Complete Profile Requestedsubfield.
 3. The method of claim 2, wherein based on the first non-APSTA requesting partial information on the first and third APs, and thepartial information on the first AP and the partial information on thethird AP are not the same, the profile field for the third AP includes asecond request element, partial information on the third link isrequested based on the second request element, and a value of the secondComplete Profile Requested subfield is set to
 0. 4. The method of claim3, wherein a value indicated by the identifier included in the firstrequest element is different from a value indicated by an identifierincluded in the second request element.
 5. The method of claim 2,wherein a fourth AP operating on a fourth link is further affiliatedwith the AP MLD, wherein a fourth non-AP STA operating on the fourthlink is further affiliated with the non-AP MLD, wherein the multi-linkelement further includes a profile field for the fourth AP, wherein theprofile field for the fourth AP includes a third Complete ProfileRequested subfield.
 6. The method of claim 5, wherein based on the firstnon-AP STA requesting the partial information on the first AP andcomplete information on the fourth AP, the complete information on thefourth AP is requested based on the profile field for the fourth AP, anda value of the third Complete Profile Requested subfield is set to
 1. 7.A first non-access point (AP) station (STA) in a wireless local areanetwork (WLAN) system, the first non-AP STA comprising: a memory; atransceiver; and a processor operatively coupled to the memory and thetransceiver, wherein processor is configured to: transmit a proberequest frame to a first AP; and receive a probe response frame from thefirst AP, wherein the first AP operating on a first link and a second APoperating on a second link are affiliated with an AP multi-link device(MLD), wherein the first non-AP STA operating on the first link and asecond non-AP STA operating on the second link affiliated with a non-APMLD, wherein based on the first non-AP STA requesting partialinformation on the first and second APs, the probe request frameincludes a first request element and a multi-link element, wherein thepartial information on the first AP is requested based on the firstrequest element, wherein the multi-link element includes a profile fieldfor the second AP, wherein the profile field for the second AP includesa first Complete Profile Requested subfield, and wherein based on thepartial information on the first AP and the partial information on thesecond AP are the same, the partial information on the second AP isrequested based on the first request element, and a value of the firstComplete Profile Requested subfield is set to
 0. 8. A method in awireless local area network (WLAN) system, the method comprising:receiving, by a first access point (AP), a probe request frame from afirst non-access point (AP) station (STA); and transmitting, by thefirst AP, a probe response frame to the first non-AP STA, wherein thefirst AP operating on a first link and a second AP operating on a secondlink are affiliated with an AP multi-link device (MLD), wherein thefirst non-AP STA operating on the first link and a second non-AP STAoperating on the second link affiliated with a non-AP MLD, wherein basedon the first non-AP STA requesting partial information on the first andsecond APs, the probe request frame includes a first request element anda multi-link element, wherein the partial information on the first AP isrequested based on the first request element, wherein the multi-linkelement includes a profile field for the second AP, wherein the profilefield for the second AP includes a first Complete Profile Requestedsubfield, and wherein based on the partial information on the first APand the partial information on the second AP are the same, the partialinformation on the second AP is requested based on the first requestelement, and a value of the first Complete Profile Requested subfield isset to
 0. 9. The method of claim 8, wherein a third AP operating on athird link is further affiliated with the AP MLD, wherein a third non-APSTA operating on the third link is further affiliated with the non-APMLD, wherein the multi-link element further includes a profile field forthe third AP, wherein the profile field for the third AP includes asecond Complete Profile Requested subfield.
 10. The method of claim 9,wherein based on the first non-AP STA requesting partial information onthe first and third APs, and the partial information on the first AP andthe partial information on the third AP are not the same, the profilefield for the third AP includes a second request element, partialinformation on the third link is requested based on the second requestelement, and a value of the second Complete Profile Requested subfieldis set to
 0. 11. The method of claim 10, wherein a value indicated bythe identifier included in the first request element is different from avalue indicated by an identifier included in the second request element.12. The method of claim 9, wherein a fourth AP operating on a fourthlink is further affiliated with the AP MLD, wherein a fourth non-AP STAoperating on the fourth link is further affiliated with the non-AP MLD,wherein the multi-link element further includes a profile field for thefourth AP, wherein the profile field for the fourth AP includes a thirdComplete Profile Requested subfield.
 13. The method of claim 12, whereinbased on the first non-AP STA requesting the partial information on thefirst AP and complete information on the fourth AP, the completeinformation on the fourth AP is requested based on the profile field forthe fourth AP, and a value of the third Complete Profile Requestedsubfield is set to 1.